JP5804256B2 - Electron spin polarized ion beam generation method and apparatus - Google Patents

Description

The present invention relates to an electron spin polarized ion beam generation method and an apparatus for generating the same.

In ion scattering spectroscopy (ISS), ions with uniform kinetic energy (hereinafter referred to as ion beams) are made incident on a solid surface of a sample, and the ions scattered in a specific direction are subjected to energy spectroscopy, so that This is a spectroscopic method for obtaining information on the structure and composition (Non-patent Document 1).
In addition, spin-polarized ion scattering spectroscopy (SP-ISS) is a spectroscopic method for obtaining information on physical properties related to spin on a solid surface by spin-polarizing incident ions of ISS (Non-patent Document 2). . In SP-ISS, detailed information can be obtained by using an electron spin-polarized ion beam having a high spin polarization rate.

The spin polarization rate is defined by the ratio of the number of ions having an upward electron spin and the number of ions having a downward electron spin. If the number of ions having an upward electron spin and the number of ions having an downward electron spin are n ↑ and n ↓, respectively, the spin polarization P is (n ↑ −n ↓) / (n ↑ + n ↓). It is prescribed by. Non-Patent Document 3 discloses a method for determining the spin polarization rate P _{He +} of a He ⁺ ion beam.

As a conventional electron spin polarized ion beam generation method, there is an optical pumping method.
Non-Patent Documents 4 and 5 describe a He ⁺ ion spin polarization method by an optical pumping method, and Non-Patent Document 6 describes a spin polarization method of various ions by an optical pumping method. .

The optical pumping method irradiates polarized light to atoms and ions (hereinafter referred to as atoms) and absorbs them in a large amount from a low energy state to a high energy state to generate a specific spin angular momentum. This is a method of generating a large number of atoms and the like to generate an electron spin polarized ion beam.

Non-Patent Document 7 describes spin-orbit interaction in ion scattering when the incident energy is 30 MeV. The spin-orbit interaction is generally an interaction that depends on the angle between vectors represented by the product S · L of the spin angular momentum S and the orbital angular momentum L. In the spin orbit interaction in the scattering, the magnetic field H and the spin S of the incident species are caused by a transient angular motion around the target nucleus of the incident species itself.

Non-Patent Document 8 describes a spin polarization method of atoms and ions by an optical pumping method, a Stern-Gerach method, and a Lamb shift method. There is an explanation that the nuclear spin of the incident species is polarized by spin-orbit interaction in ion scattering. However, there is no explanation about electron spin polarization by ion scattering.

In an apparatus using an optical pumping method, high-intensity polarized light is required. Therefore, it is necessary to highly control the laser beam. Therefore, there are restrictions and problems that the manufacturing cost of the apparatus is high, the operation is complicated, and the handling is difficult.
Accordingly, there is a need for an electron spin polarized ion beam generation method and generator that do not use an optical pumping method.

JP 2008-135308 A

M.M. Aono et al., Phys. Rev. Lett. 51 (1983) 801 T. T. et al. Suzuki, Y. et al. Yamauchi. , Surf. Sci. 602 (2008) 579. T. T. et al. Suzuki, Y. et al. Yamauchi, Physical Review A77 (2008) 0229902 D. L. Bixler and 5 others, Rev. Sci. Instr. 70 (1999) 240 T. T. et al. Suzuki, Y. et al. Yamauchi. Nucl. Instrum. Meth. Phys. Res. A575 (2007) 343 E. W. Weber. Phys. Rep. 32 (1977) 123 P. D. Greaves and three others, Nucl. Phys. A179 (1972) 1 Kenichi Kubo, Kenji Katori, “Spin and Polarization”, Bafukan

An object of the present invention is to provide an electron spin-polarized ion beam generating method and an apparatus for generating the electron spin-polarized ion beam in which the absolute value of the spin polarization rate is 0.05 or more without using the optical pumping method.

As a result of studying in view of the above circumstances, this researcher can easily extract a polarized ion beam by taking out an ion beam elastically scattered from a solid surface by using a spin polarizer comprising a target and an electrostatic analyzer. The present invention has been completed by discovering that it is possible to avoid the above-mentioned restrictions.
The basic principle of the present technology is spin-orbit interaction in elastic scattering, which can be applied not only to all ions having electron spins but also to aggregates such as atoms, ions, and ion clusters.
Further, by limiting the magnetic field arrangement, the target material, the incident energy, and the scattering angle, an ion beam having a high spin polarization rate can be obtained, which is convenient for application of a spin polarized ion beam such as SP-ISS.
The present invention has the following configuration.

(1) A step of generating an ion beam composed of rare gas element ions, a step of emitting the scattered ion beam by making the ion beam incident on one surface of the target, and taking the scattered ion beam into an electrostatic analyzer A method of generating an electron spin polarized ion beam by applying an electric field, wherein the ion beam is incident when the ion beam is incident on one surface of the target. versus the scattering plane including both the emission direction of the scattered ion beam to the direction, so that the direction of the magnetic field is the direction of 80 ° to 100 °, electrons and applying a magnetic field to said target Spin-polarized ion beam generation method.

(2) The method of generating an electron spin polarized ion beam according to (1), wherein rare gas element ions are generated by a plasma method.
(3) The method of generating an electron spin polarized ion beam according to (1) or (2), wherein the rare gas element is He.
(4) the ion beam is at the incident energy is 3 0ke V inclusive 1keV the scattering angle is 0.99 °, to one of, wherein the incident angle is 0 ° (1) ~ (3) The electron spin polarized ion beam generation method described.

(5) The electron spin polarized ion beam generation according to (4), wherein the incident angle is 0 °, and the target has one material selected from an element group having an atomic number of 50 or more. Method.
(6) The method of generating an electron spin polarized ion beam according to (5), wherein the target includes one material selected from the group consisting of Sn, Au, Pb, and Bi.
(7) The incident energy of the ion beam is 1.57 keV, the scattering angle is in the range of 60 ° to 90 ° or 110 ° to 150 °, and the incident angle is (180 ° −scattering angle) / 2. And the target is Au, The method of generating an electron spin polarized ion beam according to (1) .

(8) The incident energy of the ion beam is 1.57 keV, the scattering angle is in the range of 25 ° to 140 °, the incident angle is (180 ° −scattering angle) / 2, and the target is Pb. (1) The electron spin polarized ion beam generation method according to (1) .
(9) A step of measuring the spin asymmetry rate of an electron spin-polarized ion beam by an optical pumping method with the same kind of rare gas element, kind of target material, incident energy value, incident angle, outgoing angle, and scattering angle. The method of generating an electron spin polarized ion beam according to any one of (1) to (8), comprising:

(10) A vacuum chamber, an ion beam generation unit, a beam line connecting the vacuum chamber and the ion beam generation unit, and a vacuum chamber, the ion beam generation unit, and the beam line 3 are arranged so as to surround the vacuum chamber, the ion beam generation unit, and the beam line. An electron spin polarized ion beam generator having a shaft coil, wherein a substantially plate-like target and an electrostatic analyzer are disposed in the vacuum chamber, and the target is controlled by a rotation control mechanism. The electrostatic analyzer can be rotated about the target rotational axis by a movement control mechanism, and the three-axis coil is energized. by adjusting the current, the being capable applying a magnetic field to the target, the three-axis coil, the direction of the magnetic field, the ion beam generated from the ion beam generator wherein The magnetic field is applied to the target so as to be in the direction of 80 ° or more and 100 ° or less with respect to the scattering surface including both the incident direction of incident light and the exit direction of emission of the ion beam scattered by the target. electron spin polarized ion beam generator, wherein the applied child.

(11) The electrostatic analyzer includes a cylindrical portion and an electric field applying member disposed so as to surround the cylindrical portion, and an electric field can be applied to the ion beam in the cylindrical portion (10). The electron spin polarized ion beam generator described in (1).
(12) The electron spin polarized ion beam generator according to (10) or (11), wherein the ion beam generator is an RF discharge tube to which a rare gas element gas introduction tube is connected.

The method of generating an electron spin polarized ion beam according to the present invention includes a step of generating an ion beam composed of rare gas element ions, a step of emitting the scattered ion beam by making the ion beam incident on one surface of the target, and the scattering A method of generating an electron spin-polarized ion beam by taking an ion beam into an electrostatic analyzer and applying an electric field to generate the electron spin-polarized ion beam. When the light is incident on the target, the magnetic field is applied to the target so that the direction of the magnetic field is 80 ° or more and 100 ° or less with respect to the scattering surface including both the incident direction of the ion beam and the emitting direction of the scattered ion beam. Since the field is applied, an electron spin-polarized ion beam having an absolute value of spin polarization of 0.05 or more is generated without using the optical pumping method. Can do.

An electron spin polarized ion beam generator according to the present invention includes a vacuum chamber, an ion beam generator, a beam line connecting the vacuum chamber and the ion beam generator, the vacuum chamber, the ion beam generator, and An electron spin polarized ion beam generator provided with a three-axis coil arranged so as to surround the beam line, and a substantially plate-like target and an electrostatic analyzer are arranged in the vacuum chamber, The target can be rotated about a rotation axis parallel to one surface of the target by a rotation control mechanism, and the electrostatic analyzer can be rotated about the rotation axis of the target by a movement control mechanism. and, by adjusting the current supplied to the three-axis coil, said target being capable applying a magnetic field to the three-axis coil, the direction of the magnetic field, the ion beam A direction of 80 ° or more and 100 ° or less with respect to a scattering surface including both an incident direction in which an ion beam generated from a raw part enters the target and an exit direction in which the ion beam scattered by the target exits. Thus, since the magnetic field is applied to the target , an electron spin-polarized ion beam having an absolute value of the spin polarization of 0.05 or more can be generated without using an optical pumping method.

It is a perspective view which shows an example of the electron spin polarization ion beam generator of this invention. It is a figure which shows the path | route of the ion beam produced | generated by the ion beam generation part. It is a figure which shows an example of a target, a magnetic field direction, the irradiation direction of an ion beam, and a scattering direction. 4A and 4B are diagrams illustrating an electrostatic analyzer, in which FIG. 4A is a plan view, and FIG. 4B is a cross-sectional view taken along line A-A ′ of FIG. A graph showing the spin asymmetry A _{(He +, Au, 1.54, 0, 30, 150)} obtained as a function of the kinetic energy of the scattered ions, and the kinetic energy of the scattered ions and the scattered ion intensity I _{(integrated value)} . It is a graph which shows the ISS spectrum which shows a relationship. It is a graph which shows the relationship between spin-polarization rate PHe _{+ (OUTPUT)} and the atomic number of a target material. It is a graph which shows the relationship between spin-polarization rate PHe _{+ (OUTPUT)} and incident energy. It is a graph which shows the relationship between spin-polarization rate PHe _{+ (OUTPUT)} and scattering angle ₍ theta ₎ .

(Embodiment of the present invention)
<Electron spin polarized ion beam generator>
First, an electron spin polarized ion beam generator according to an embodiment of the present invention will be described.
FIG. 1 is a perspective view showing an example of an electron spin polarized ion beam generator according to an embodiment of the present invention.
As shown in FIG. 1, an electron spin polarized ion beam generator 51 according to an embodiment of the present invention is schematically configured to include a vacuum chamber 10 and an ion beam generator 1.
The vacuum chamber 10 and the ion beam generator 1 are surrounded by a triaxial coil 11. The triaxial coil 11 has a length of one side L and is formed in a cubic shape. The current flowing through the triaxial coil 11 is adjusted, for example, to change the direction of the magnetic field from the ion beam generator 1 to the vacuum chamber 10. The vertical direction shown in FIG. 1 is set to be about 3 × 10 ⁻⁵ T. The length of one side L is 2 m, for example.

The ion beam generator 1 is connected to a vacuum chamber 10 by a beam line 6. Exhaust pipes 7 and 8 connected to a vacuum pump (not shown) are connected to the beam line 6, and the base pressure is 5 × 10 ⁻ inside the vacuum chamber 10, the beam line 6, and the ion beam generator 1. ^The pressure can be reduced to ¹¹ Torr or less.

The ion beam generator 1 is an RF discharge tube to which a rare gas element gas introduction tube 2 and an exhaust tube 3 are connected. The noble gas element can be ionized by discharging the noble gas introduced from the noble gas element gas introduction pipe 2 into plasma.
The ion beam generator 1 is not limited to the RF discharge tube, but may be any device that can ionize a rare gas element.

The ion beam generator 1 is made of a material having high light transmittance. Thereby, the rare gas element can be spin-polarized by the optical pumping method in which the rare gas element ions are irradiated with two kinds of light 4 and 5. With this configuration, the spin polarization can be easily obtained by the optical pumping method. Furthermore, based on the spin polarization, the value of the spin polarization obtained by the electron spin polarization ion beam generation method and apparatus according to the embodiment of the present invention can be easily calculated.
However, in the embodiment of the present invention, since the spin polarization of the rare gas element ion is possible with the spin polarizer in the vacuum chamber 10, the method and apparatus for generating the electron spin polarized ion beam include this configuration (ion The configuration in which the beam generating unit 1 is formed of a material having high light transmittance is not necessary. The value of the spin polarization obtained by the electron spin polarized ion beam generation method and apparatus according to the embodiment of the present invention may be calculated based on the spin polarization obtained by another means.

As the rare gas element, for example, helium (He) can be used. An ion beam made of He ⁺ ions is easy to handle. However, the present invention is not limited to this, and Ne, Ar, Kr, Xe, or the like may be used.

The beam line 6 is provided with an electric field application mechanism (not shown). By applying a rare gas element ion in the direction of the vacuum chamber 10 from the ion beam generator 1 and accelerating it, an ion beam can be obtained. it can.

A rotation control mechanism (target manipulator) 9 is provided in the upper part of the vacuum chamber 10. By rotating the rotation control mechanism 9, the target in the vacuum chamber 10 can be rotated around a certain rotation axis.

FIG. 2 is a diagram showing a path of an ion beam generated by the ion beam generator.
As shown in FIG. 2, a spin polarizer 14 is installed in the vacuum chamber 10. The spin polarizer 14 includes a substantially plate-like target 12 and an electrostatic analyzer 13.
A magnetic field can be applied to the target 12 by a triaxial coil 11 disposed so as to surround the vacuum chamber 10.

The target 12 can be rotated about the rotation axis g by rotating the rotation control mechanism (target manipulator) 9. The rotation axis g is perpendicular to the scattering plane including both the incident direction and the outgoing direction.
The electrostatic analyzer 13 can be rotated and moved around the rotation axis g of the target 12 with the opening 13c1a facing the target 12 by a movement control mechanism (not shown). That is, it is movable on the same axis as the rotation axis g of the target 12.

As the material for the target 12, all elements can be used. This is because the spin-orbit interaction, which is the principle, works if the target nucleus has a charge. When at least silicon, copper, zinc, silver, tin, gold, lead, and bismuth are used, an electron spin polarized ion beam can be generated.
For example, when single crystal gold (Au) is used, the (111) plane is set as an ion beam irradiation surface.

As the material of the target 12, a material having a large atomic number is preferable. By using a material having a large atomic number, the spin polarization can be improved.

The ion beam generated by the ion beam generator 1 is subjected to electric field movement in the beam line 6 and irradiated onto the one surface 12 a of the target 12 in the vacuum chamber 10.
The ion beam scattered by the one surface 12a of the target 12 is taken into the inside through the opening 13c1a of the electrostatic analyzer 13.
In the electrostatic analyzer 13, the ion beam is subjected to an electric field application process, and an ion beam having kinetic energy corresponding to elastic scattering is taken out to be an electron spin-polarized ion beam, which is then emitted from the opening 13 c 2 b. .

A secondary electron multiplier 15 is installed below the electrostatic analyzer 13. The secondary electron multiplier 15 can measure the output signal of He ⁺ ions by taking in the ion beam emitted from the electrostatic analyzer 13.
A preamplifier (not shown) is connected to the secondary electron multiplier 15 so that an output signal can be amplified. A computer is connected to the preamplifier via a counter board so that the output signal can be processed by the computer.
The secondary electron multiplier 15 can be removed, and a sample can be arranged instead of the secondary electron multiplier 15. By arranging the sample, it is possible to analyze the solid surface of the sample by irradiating the sample with an electron spin polarized ion beam.

FIG. 3 is a diagram illustrating an example of a target, a magnetic field direction, and an ion beam irradiation direction / scattering direction.
As shown in FIG. 3, the normal direction of the one surface 12a of the target 12 is set to be substantially perpendicular to the magnetic field direction. An incident angle α, an outgoing angle β, and a scattering angle θ of the ion beam are displayed. A plane (scattering plane) including both the incident direction and the outgoing direction is adjusted to be parallel to the normal direction.

By adjusting the coil current of the three-axis coil, the normal direction of the one surface 12a of the target 12 can be set in a direction substantially perpendicular to the magnetic field direction.
By rotating the target 12, the incident angle α can be set in the range of 0 ° or more and less than 90 °. Further, by moving the electrostatic analyzer 13, the scattering angle θ can be set in a range of 0 ° to less than 180 °. The exit angle β is determined by setting the incident angle α and the scattering angle θ.

The magnetic field direction is preferably a direction substantially perpendicular to the scattering plane including both the incident direction of the ion beam and the emitting direction of the scattered ion beam. This is because the spin-orbit interaction can be maximized and the obtained spin polarization can be maximized.
Specifically, the direction of the magnetic field is preferably 80 ° or more and 100 ° or less with respect to the normal direction of the one surface 12a of the target 12, and the direction of the magnetic field is 85 ° or more and 95 ° or less. More preferably, it is more preferably 90 °.
The magnetic field direction need not be a direction parallel to the scattering surface. This is because spin-orbit interaction occurs unless the magnetic field direction and the scattering surface are parallel.

4A and 4B are diagrams illustrating an example of the electrostatic analyzer 13, in which FIG. 4A is a plan view, and FIG. 4B is a cross-sectional view taken along the line AA ′ in FIG. .
As shown in FIG. 4A, the electrostatic analyzer 13 is formed by connecting members 13a and 13b having a substantially rectangular shape in plan view. Cylindrical portions 13c1 and 13c2 are provided on the substantially rectangular members 13a and 13b in plan view, respectively.

As shown in FIG. 4B, a side view semicircular member 13a and a side view 1/4 circle (fan) shape 13b are coupled so as to communicate the cylindrical portions 13c1 and 13c2.
The member 13a includes electric field applying members 13a1 and 13a2, and an insulating member (not shown) is sandwiched. Thus, an electric field can be applied between the electric field applying members 13a1 and 13a2, and an ion beam having a specific kinetic energy can pass through the cylindrical portion 13c1 by manipulating the direction and magnitude of the electric field. .

Similarly, the member 13b includes electric field applying members 13b1 and 13b2, and an insulating member (not shown) is sandwiched therebetween. As a result, an electric field can be applied between the electric field applying members 13b1 and 13b2, and an ion beam having specific kinetic energy can pass through the cylindrical portion 13c2 by manipulating the direction and magnitude of the electric field. it can.

The He ⁺ ions scattered by the target 12 are taken into the electrostatic analyzer 13 from the opening 13c1a, and then the energy is fractionated by the sweep voltage in the electrostatic analyzer 13, and the ion beam has a kinetic energy corresponding to elastic scattering. Is extracted into an electron spin-polarized ion beam and emitted from the other opening 13c2b.

<Method of generating electron spin polarized ion beam>
Next, a method for generating an electron spin polarized He ⁺ ion beam according to an embodiment of the present invention will be described.
An electron spin polarized He ⁺ ion beam generating method according to an embodiment of the present invention includes an ion beam generating step S1, a scattered ion beam generating step S2, and an electron spin polarized ion beam generating step S3.

(Ion beam generation step S1)
First, the triaxial coil is adjusted so that the magnetic field direction from the He ⁺ ion source to the vacuum chamber is parallel to the vertical direction, and the size is in the range of 1 × 10 ⁻⁶ T to 1 × 10 ⁻⁴ T. Adjust as follows.

The target material is any of the materials described above and is denoted by M.
For example, single crystal gold (Au) is used, and in the following process, the (111) plane is set in the vacuum chamber so that the (111) plane is parallel to the target rotation axis so that the (111) plane is the ion beam irradiation surface. Place the target on. In this arrangement, the plane (scattering plane) including both the incident direction and the outgoing direction is parallel to the normal direction of the target surface.

Next, the magnetic field correcting triaxial coil is adjusted so that the magnetic field direction is perpendicular to the scattering surface.
As a result, the magnetic field direction is in the range of 80 ° to 100 ° with respect to the normal direction of one surface of the target, and the incident angle α, the outgoing angle β, and the scattering angle θ are set to predetermined values.

Next, the vacuum chamber, the beam line, and the RF discharge tube are depressurized by a vacuum pump. For example, the base pressure is set to an ultrahigh vacuum of 5 × 10 ⁻¹¹ Torr or less.

Next, helium gas is introduced into the RF discharge tube from the rare gas element gas inlet. Further, exhaust is performed from the rare gas element gas exhaust port, and for example, the helium pressure in the RF discharge tube is adjusted to about 20 Pa.

Next, the He gas is discharged by setting the RF output to any value in the range of 1 W to 10 W, and helium plasma is generated in the RF discharge tube to generate unpolarized He ⁺ ions.

Next, one surface of the target is cleaned by a combination of heat treatment in ultrahigh vacuum and ion beam sputtering. The cleanliness of the target surface is confirmed by whether or not only the elastically scattered ion peak of the target material is observed by scattering ion spectroscopy (ion scattering spectroscopy (ISS)) using an electrostatic analyzer.

(Scattered ion beam generation step S2)
Next, an electric field is applied to the beam line, unpolarized He ⁺ ions are accelerated and transported to a spin polarizer installed in a vacuum chamber, and an ion beam composed of He ⁺ ions is incident with energy E. Irradiate the target in the spin polarizer in the vacuum chamber.
He ⁺ ions are scattered at the target, generating a scattered ion beam.

The scattering angle and 0.99 °, if the incident angle is 0 °, the incident energy E is preferably set to 3 0ke V less than 1 keV. By setting the incident energy E to 1 keV or more, a spin-polarized ion beam can be efficiently generated by efficient spin-orbit interaction. If the incident energy E is 30 keV or higher, it is unclear whether spin-orbit interaction in ion scattering is shown.

The scattering angle and 0.99 °, angle of incidence was set at 0 °, if the incident energy E was 3 0ke V less than 1 keV, the target preferably has one material selected from atomic number 50 No. of element groups . In particular, it is preferred that the target has one material selected from the group of Sn, Au, Pb, Bi. The absolute value of the spin polarization can be made 0.05 or more.

When the incident energy of the ion beam is 1.57 keV and the target is Au, the scattering angle is in the range of 60 ° to 90 ° or 110 ° to 150 °, and the incident angle is (180 ° −scattering angle). ) / 2. The absolute value of the spin polarization can be made 0.05 or more.

When the incident energy of the ion beam is 1.57 keV and the target is Pb, the scattering angle is in the range of 25 ° to 140 °, and the incident angle is (180 ° −scattering angle) / 2. preferable. The absolute value of the spin polarization can be made 0.05 or more.

(Electron spin polarized ion beam generation step S3)
Next, He ⁺ ions elastically scattered by the target are taken into the electrostatic analyzer from the opening.
He ⁺ ions scattered by the target are taken into the electrostatic analyzer from the opening, and then the energy is separated by the sweep voltage in the electrostatic analyzer, and an ion beam having a kinetic energy corresponding to elastic scattering is taken out. Thus, an electron spin-polarized ion beam is generated and emitted from the other opening.
When He ⁺ ions are used as the rare gas element ions, a spin-polarized He ⁺ ion beam is emitted from the other opening.

(Spin Polarization Ratio Calculation Step S4 of Electron Spin Polarized Ion Beam)
An output signal (scattered ion intensity I _{(integrated value)} ) of spin-polarized He ⁺ ions that have passed through the electrostatic analyzer is measured for a predetermined time with a secondary electron multiplier installed at the bottom of the electrostatic analyzer. The predetermined time is not less than 100 seconds and not more than 10,000 seconds. If the predetermined time is less than 100 seconds, evaluation data that can be evaluated cannot be obtained. On the other hand, if it exceeds 10,000 seconds, there is a possibility that the characteristics of the target deteriorate.

Next, the measurement data is amplified by a preamplifier, then counted using a counter board, and processed by a computer to calculate scattered ion intensity I _{(integrated value)} .
Scattered ion intensity I _{(integrated value)} is obtained as a function of scattered ion kinetic energy and gives an ISS spectrum. The kinetic energy of the scattered ions is given as a function of the electrostatic analyzer sweep voltage.

From the spin asymmetry A _{(He +, M, E, α, β, θ) at} the kinetic energy of the scattered ion that gives the peak value of the scattered ion intensity I _{(integrated value)} , the spin polarization He ⁺ ion beam spin polarization rate P _{He + (OUTPUT)} is obtained.
The spin asymmetry rate A _{(He +, M, E, α, β, θ)} uses a He ⁺ ion beam, a material M as a target, an incident energy E, an incident angle α, an outgoing angle β, and a scattering angle θ. Is the spin asymmetry rate.

[Method for determining spin asymmetry A _{(He +, M, E, α, β, θ)} ]
Next, a method for determining the spin asymmetry A of the He ⁺ ion beam will be described.
As a method for determining the spin asymmetry A, for example, an optical pumping method is used.

First, the triaxial coil is adjusted so that the magnetic field from the He ⁺ ion source to the vacuum chamber is parallel to the vertical direction and the magnitude is in the range of 1 × 10 ⁻⁶ T to 1 × 10 ⁻⁴ T. Adjust to.

The target material consists of M. M is any of the materials described above.
For example, single crystal gold (Au) is used, and in the following steps, the (111) plane is set in the vacuum chamber so that the (111) plane is parallel to the target rotation axis so that the (111) plane is the irradiation surface of the ion beam. Place the target on. In this arrangement, the plane (scattering plane) including both the incident direction and the outgoing direction is parallel to the normal direction of the target surface.

Next, the magnetic field correcting triaxial coil is adjusted so that the magnetic field direction is perpendicular to the scattering surface.
As a result, the magnetic field direction is in the range of 80 ° to 100 ° with respect to the normal direction of one surface of the target, and the incident angle α, the outgoing angle β, and the scattering angle θ are set to predetermined values.

Next, the vacuum chamber, the beam line, and the RF discharge tube are depressurized by a vacuum pump. For example, the base pressure is set to an ultrahigh vacuum of 5 × 10 ⁻¹¹ Torr or less.

Next, helium gas is introduced into the RF discharge tube from the rare gas element gas inlet. Further, exhaust is performed from the rare gas element gas exhaust port, and for example, the helium pressure in the RF discharge tube is adjusted to about 20 Pa.

Next, the He gas is discharged with an RF output in the range of 1 W to 10 W to generate helium plasma in the RF discharge tube to generate He ⁺ ions.

Next, one surface of the target is cleaned by a combination of heat treatment in ultrahigh vacuum and ion beam sputtering. The cleanliness of the target surface is confirmed by whether or not only the elastically scattered ion peak of the target material is observed by scattering ion spectroscopy (ion scattering spectroscopy (ISS)) using an electrostatic analyzer.

“Process to measure output signal by turning helicity of circularly polarized light pumping light clockwise”
Next, the He ⁺ ions in the RF discharge tube are spin-polarized by an optical pumping method.
Specifically, the optical pumping radiation beam of the linearly polarized light, is irradiated with optical pumping radiation light circularly polarized light at the same time He ⁺ ions, to generate spin-polarized He ⁺ ions.
The helicity of the circularly polarized light pumping irradiation light (the direction of the spin with respect to the direction of motion) is controlled clockwise so that the spin direction of the spin-polarized He ⁺ ion is parallel to the direction of the magnetic field.
Incidentally, for example, the wavelength of optical pumping radiation beam is adjusted to _{D 0} line of 1083 nm, it is adjusted so that the optical density is approximately 0.1 W / cm ^2.

Next, an electric field is applied to the beam line, the spin-polarized He ⁺ ions are accelerated and transported to a spin polarizer installed in a vacuum chamber, and the incident energy of the ion beam composed of He ⁺ ions is expressed as E The target in the spin polarizer in the vacuum chamber is irradiated.

He ⁺ ions are scattered by the target and then taken into the electrostatic analyzer, pass through the electrostatic analyzer, and are emitted from the bottom of the electrostatic analyzer.
In the electrostatic analyzer, He ⁺ ions scattered by the target are applied with an electric field, so that He ⁺ ions having a specific kinetic energy pass through the electrostatic analyzer. It is the sweep voltage of the electrostatic analyzer that defines this specific kinetic energy.
When the spin-polarized He ⁺ ion spin direction is parallel to the magnetic field direction, the output signal of the spin-polarized He ⁺ ion passing through the electrostatic analyzer (scattered ion intensity I _{↑ (first time)} ) Measurement is performed for a predetermined time with a secondary electron multiplier installed at the bottom of the electrostatic analyzer.
The predetermined time is, for example, 10 seconds.

“Process to measure output signal by turning counterclockwise helicity of circularly polarized light pumping light”
Next, except that the helicity of the circularly polarized light pumping irradiation light is controlled counterclockwise so that the spin direction of the spin-polarized He ⁺ ion is antiparallel to the direction of the magnetic field, in the same way as in the clockwise "helicity, spin-polarized He ⁺ when the spin direction was antiparallel direction of the magnetic field of the ion, the spin-polarized He ⁺ ions of the output signal (scattered ionic strength I _{↓ (First time)} ) is measured for a predetermined time with a secondary electron multiplier installed in the lower part of the electrostatic analyzer. The predetermined time is, for example, 10 seconds.

The process of measuring the output signal by turning the helicity of the circularly polarized light pumping irradiation clockwise and the process of measuring the output signal by turning the helicity of the circularly polarized light pumping light counterclockwise are repeated several times alternately. After obtaining each measurement data, the measurement data is amplified by a preamplifier, then counted using a counter board, and processed by a computer so that the spin direction of spin-polarized He ⁺ ions is parallel to the direction of the magnetic field. In this case, the scattered ion intensity I _{↑ (integrated value)} and the scattered ion intensity I _{↓ (integrated value)} when the spin direction of the spin-polarized He ⁺ ion is antiparallel to the magnetic field direction are calculated.
The scattered ion intensity I _{↑ (integrated value)} and scattered ion intensity I _{↓ (integrated value)} are each obtained as a function of the scattered ion kinetic energy.

The reason why the spin direction of the He ⁺ ion is periodically switched between parallel and antiparallel is to eliminate the influence of the surface change of the target over time. It is preferable to switch at least 100 times or more.

Next, the scattered ion intensity I _{↑ (integrated value)} and scattered ion intensity I _{↓ (integrated value),} and the incident He ⁺ ion beam spin polarization rate PHe _{+ (INPUT)} defined by the following equation (2) are as follows. Substitute into equation (1). In Equation (2), n ↑ is the number of He ⁺ ions having a magnetic moment parallel to the magnetic field, and n ↓ is the number of He ⁺ ions having a magnetic moment antiparallel to the magnetic field. A known value can be used as the spin polarization rate P _{He + (INPUT)} .
Spin asymmetry A _{(He +, M, E, α, β, θ)} is obtained as a function of the kinetic energy of the scattered ions.

The scattered ion intensities I _{↑ (integrated value)} and I _{↓ (integrated value))} are expressed by the following equations (3) and (4) based on the spin-orbit interaction, respectively.
Here, σ ↑ and σ ↓ are the scattering cross sections of He ⁺ ions having magnetic moments parallel and antiparallel to the magnetic field (probability of changing the trajectory of particles emitted linearly), respectively.

When the proportional coefficients of equations (3) and (4) are the same, substituting equations (3) and (4) into equation (1) yields the following equation (5).
As shown in equation (5), A _{((M, E, α, β, θ)} is composed of scattering cross sections σ ↑ and σ ↓.

Equation (5) shows that when an unpolarized He ⁺ ion beam is used, the spin asymmetry A _{(He +, M, E, α, β, θ)} of the outgoing spin polarized He ⁺ ion beam is expressed by the spin polarization. emitting spin-polarized He ⁺ ion beam spin asymmetry ratio a in the case of using two kinds of He ⁺ ion beam was very a _{(He +, M, E,} α, β, θ) and to be a same value Show.

In other words, if the spin polarization rate P _{He + (INPUT)} is known He ⁺ ion beam outgoing spin polarization He ⁺ ion beam spin asymmetry A _{(He +, M, E, α, β, θ)} , Equal to the spin polarization P _{He + (OUTPUT)} obtained by scattering an unpolarized He ⁺ ion beam under the same conditions.

An electron spin polarized ion beam generation method according to an embodiment of the present invention includes a step of generating an ion beam made of rare gas element ions, and a step of emitting the scattered ion beam by making the ion beam incident on one surface of the target A method of generating an electron spin polarized ion beam by taking the scattered ion beam into an electrostatic analyzer and applying an electric field to generate an electron spin polarized ion beam, wherein the ion beam When the light is incident on one surface of the target, the direction of the magnetic field is 80 ° or more and 100 ° or less with respect to the scattering surface including both the incident direction of the ion beam and the emitting direction of the scattered ion beam. Since the magnetic field is applied, an electron spin-polarized ion beam having an absolute value of spin polarization of 0.05 or more is generated without using the optical pumping method. be able to.

Since the electron spin polarized ion beam generation method according to the embodiment of the present invention is configured to generate rare gas element ions by the plasma method, it is possible to efficiently generate an ion beam composed of unpolarized rare gas element ions. An electron spin-polarized ion beam having an absolute value of spin polarization of 0.05 or more can be generated without using an optical pumping method.

In the electron spin polarized ion beam generating method according to the embodiment of the present invention, since the rare gas element is He, it is possible to efficiently generate an ion beam made of unpolarized He ⁺ ions, Without using the pumping method, it is possible to generate an electron spin-polarized ion beam having an absolute value of spin polarization of 0.05 or more.

Electron spin polarized ion beam generating method which is an embodiment of the invention, the incident energy of the ion beam is at 3 0ke V less than 1 keV, the scattering angle is 0.99 °, a constitution in incident angle is 0 ° It is possible to efficiently generate a spin-polarized scattered ion beam, and to generate an electron spin-polarized ion beam having an absolute value of spin polarization of 0.05 or more without using an optical pumping method. it can.

The electron spin polarized ion beam generation method according to the embodiment of the present invention has an incident angle of 0 °, and the target has a single material selected from an element group having an atomic number of 50 or more. Well, a spin-polarized scattered ion beam can be generated, and an electron spin-polarized ion beam having an absolute value of spin polarization of 0.05 or more can be generated without using an optical pumping method.

In the electron spin polarized ion beam generation method according to the embodiment of the present invention, since the target has one material selected from the group of Sn, Au, Pb, and Bi, the spin polarized scattering is efficiently performed. An ion beam can be generated, and an electron spin-polarized ion beam having an absolute value of spin polarization of 0.05 or more can be generated without using an optical pumping method.

In an electron spin polarized ion beam generation method according to an embodiment of the present invention, the ion beam has an incident energy of 1.57 keV and a scattering angle in a range of 60 ° to 90 ° or 110 ° to 150 °. Yes, since the incident angle is (180 ° −scattering angle) / 2 and the target is Au, it is possible to efficiently generate a spin-polarized scattered ion beam without using an optical pumping method, An electron spin-polarized ion beam having an absolute value of spin polarization of 0.05 or more can be generated.

In an electron spin polarized ion beam generation method according to an embodiment of the present invention, the incident energy of the ion beam is 1.57 keV, the scattering angle is in the range of 25 ° to 140 °, and the incident angle is (180 (° -scattering angle) / 2, and the target is Pb, so that a spin-polarized scattered ion beam can be generated efficiently, and the absolute value of the spin polarization rate is not used without using the optical pumping method. It is possible to generate an electron spin polarized ion beam having a thickness of 0.05 or more.

An electron spin-polarized ion beam generation method according to an embodiment of the present invention includes an electron pumping method in which a rare gas element type, a target material type, an incident energy value, an incident angle, an outgoing angle, and a scattering angle are the same. Since the configuration includes a step of measuring the spin asymmetry rate of the spin-polarized ion beam, the absolute value of the spin-polarization rate of the generated electron spin-polarized ion beam can be calculated without using the optical pumping method.

An electron spin polarized ion beam generator according to an embodiment of the present invention includes a vacuum chamber, an ion beam generator, a beam line connecting the vacuum chamber and the ion beam generator, the vacuum chamber, and the ion. An electron spin polarized ion beam generator comprising a beam generator and a three-axis coil arranged so as to surround the beam line, wherein a substantially plate-like target and an electrostatic analyzer are arranged in the vacuum chamber The target can be rotated about a rotation axis parallel to one surface of the target by a rotation control mechanism, and the electrostatic analyzer can be rotated about the rotation axis of the target by a movement control mechanism. Since it is configured to be movable and a magnetic field can be applied to the target by adjusting the current applied to the triaxial coil, the optical pumping method is not used, and the spin is not used. The absolute value of the polarization degree can be generated electrons spin-polarized ion beam is 0.05 or more.

In an electron spin polarized ion beam generator according to an embodiment of the present invention, the electrostatic analyzer includes a cylindrical portion and an electric field applying member disposed so as to surround the cylindrical portion. Since an electric field can be applied, an electron spin-polarized ion beam having an absolute value of spin polarization of 0.05 or more can be efficiently generated by spin-orbit interaction without using an optical pumping method. it can.

In the electron spin polarized ion beam generator according to an embodiment of the present invention, the ion beam generator is an RF discharge tube to which a rare gas element gas introduction tube is connected. An ion beam composed of gas element ions can be generated, and an electron spin-polarized ion beam having an absolute value of spin polarization of 0.05 or more can be generated without using an optical pumping method.

The electron spin-polarized ion beam generation method and the generation apparatus according to the embodiment of the present invention are not limited to the above-described embodiment, and may be implemented with various modifications within the scope of the technical idea of the present invention. Can do. Specific examples of this embodiment are shown in the following examples. However, the present invention is not limited to these examples.

(Example 1)
[Spin Asymmetry A _{(He +, Au, 1.54, 0, 30, 150)} Determination Step]
(Preparation process)
First, an experiment was performed to determine the spin asymmetry ratio A _{(He +, Au, 1.54, 0, 30, 150)} of the He ⁺ ion beam.
The spin asymmetry A _{(He +, Au, 1.54, 0, 30, 150)} uses a He ⁺ ion beam, Au as a target, an incident energy of 1.54 eV, an incident angle α = 0 °, and an output. The spin asymmetry rate when the angle β = 30 ° and the scattering angle θ = 150 °.

First, a triaxial coil having a side L of 2 m is adjusted so that the magnetic field from the He ⁺ ion source to the vacuum chamber is parallel to the vertical direction and the size is about 3 × 10 ⁻⁵ T. Adjusted.
Single crystal gold (Au) was used as a target, and the (111) plane was used as the ion beam irradiation surface. The target was placed so that the (111) plane was parallel to the target rotation axis.

Next, the magnetic field correction three-axis coil was adjusted so that the magnetic field was perpendicular to the scattering surface.
Thereby, the magnetic field was applied so that the direction of the magnetic field was 80 ° or more and 100 ° or less with respect to the normal direction of one surface of the target. Further, the incident angle α = 0 °, the outgoing angle β = 30 °, and the scattering angle θ = 150 °.

Next, the inside of the vacuum chamber, the beam line, and the RF discharge tube were depressurized by a vacuum pump, and the base pressure was set to an ultrahigh vacuum of 5 × 10 ⁻¹¹ Torr or less.

Next, helium gas was introduced into the RF discharge tube from the rare gas element gas inlet. Further, exhaust was performed from a rare gas element gas exhaust port, and the helium pressure in the RF discharge tube was adjusted to about 20 Pa.

Next, the He gas was discharged with an RF output of 3 W to generate helium plasma in the RF discharge tube, thereby generating He ⁺ ions.

Next, one surface of the target was cleaned by a combination of heat treatment in ultrahigh vacuum and ion beam sputtering. The cleanliness of the target surface was confirmed by whether or not only the elastic scattering ion peak of the target material was observed by scattering ion spectroscopy (ion scattering spectroscopy (ISS)) using an electrostatic analyzer.

“Process to measure output signal by turning helicity of circularly polarized light pumping light clockwise”
Next, He ⁺ ions in the RF discharge tube were spin-polarized by an optical pumping method.
Specifically, the optical pumping radiation beam of the linearly polarized light is irradiated at the same time He ⁺ ions optical pumping radiation light circularly polarized light was generated spin-polarized He ⁺ ions. The wavelength of the light pumping irradiation light was adjusted to 1083 nm D ₀ line, and the light density was adjusted to about 0.1 W / cm ² .
In addition, the helicity of the circularly polarized light pumping irradiation light was controlled clockwise so that the spin direction of the spin-polarized He ⁺ ion was parallel to the direction of the magnetic field.

Then, an electric field is applied to the beam line, to accelerate the He ⁺ ions obtained by spin-polarized transported to spin-polarized instrument installed in a vacuum chamber, He ⁺ ion beam incident energy 1 consisting of ions. The target was made of Au (111) in the spin polarizer in the vacuum chamber at 54 keV.

The He ⁺ ions were scattered by the target, then taken into the electrostatic analyzer, passed through the electrostatic analyzer, and emitted from the bottom of the electrostatic analyzer.
The output signal (scattered ion intensity I _{↑ (first time)} ) of spin-polarized He ⁺ ions that passed through the electrostatic analyzer was measured for 10 seconds with a secondary electron multiplier installed at the bottom of the electrostatic analyzer.

“Process to measure output signal by turning counterclockwise helicity of circularly polarized light pumping light”
Next, except that the helicity of the circularly polarized light pumping irradiation light is controlled counterclockwise so that the spin direction of the spin-polarized He ⁺ ion is antiparallel to the direction of the magnetic field, As in the case of “clockwise helicity”, the output signal of the spin-polarized He ⁺ ion (scattered ion intensity I _{↓ (first time)} ) is sent to the secondary electron multiplier installed at the bottom of the electrostatic analyzer. Measurement was performed for 10 seconds.

The step of measuring the output signal by turning the helicity of the circularly polarized light pumping light clockwise and the step of measuring the output signal by turning the helicity of the circularly polarized light pumping light counterclockwise are repeated 100 times alternately. After each measurement data is obtained, the measurement data is amplified by a preamplifier, counted using a counter board, processed by a computer, and scattered ion intensity I _{↑ (integrated value)} and scattered ion intensity I _{↓ (integrated) Value)} .

Next, the scattered ion intensity I _{↑ (integrated value), the} scattered ion intensity I _{↓ (integrated value),} and the incident He ⁺ ion beam spin polarization rate PHe _{+ (INPUT)} defined by Expression (2) are _expressed by Expression (1 _). ). A known value was used for the spin polarization rate P _{He + (INPUT)} .
FIG. 5 shows the spin asymmetry A _{(He +, Au, 1.54, 0, 30, 150)} obtained as a function of the kinetic energy of the scattered ions.

As shown in FIG. 5, when the kinetic energy of scattered ions was 30 eV, the spin asymmetry A _{(He +, Au, 1.54, 0, 30, 150)} was 0.0. Further, when the kinetic energy of the scattered ions was 1250 eV, the spin asymmetry A _{(He +, Au, 1.54, 0, 30, 150)} was −0.17 to +0.16. In addition, when the kinetic energy of scattered ions was 1550 eV, the spin asymmetry A _{(He +, Au, 1.54, 0, 30, 150)} was −0.22 to 0.20. Further, the spin asymmetry A _{(He +, Au, 1.54,} 0 _{, 30, 150)} was in the range of 0 to −0.1 when the kinetic energy of scattered ions was in the range of 1250 to 1550 eV.

In FIG. 5, error bars based on statistical errors are added, but considering this, the statistically significant absolute value of the spin asymmetry becomes maximum in the vicinity of 1410 eV corresponding to the elastic scattering energy, and the value is 0. 0.09.

<Electron spin polarized He ⁺ ion beam generation process>
Next, without using the optical pumping method, an ion beam composed of unpolarized He ⁺ ions is transported to a spin polarizer installed in the vacuum chamber using a beam line, and the spin polarization in the vacuum chamber is performed. The output signal of the spin-polarized He ⁺ ion (scattered ion intensity) is the same as in the case where “the helicity of the circularly polarized light pumping irradiation light is clockwise” except that the target made of Au (111) is irradiated in the chamber. I _{(integrated value)} ) was measured for 1000 seconds with a secondary electron multiplier installed at the bottom of the electrostatic analyzer.

Thereby, as shown in FIG. 5, the ISS spectrum which shows the relationship between the kinetic energy of scattered ion and scattered ion intensity _| strength I _{(integrated value)} was obtained.
As shown in FIG. 5, ISS spectra of 50 eV peak and 1410 eV peak were obtained. The 50 eV peak is composed of secondary ions, and the 1410 eV peak is a gold elastic scattering ion peak.
Since this ISS spectrum corresponds to the spin asymmetry A _{(He +, Au, 1.54, 0, 30, 150)} , the scattering He + having a spin polarization PHE _{+ (OUTPUT)} of 9% at the 1410 eV peak value. An ion beam was obtained.

(Example 2)
<About the atomic number dependence of the target material>
Circularly polarized light pumping in the same manner as in Example 1 except that the target material is any one of Si, Cu, Zn, Ag, Sn, Au, Pb, and Bi, and the incident energy is 1.4 to 1.7 keV. Each measurement data is obtained by alternately repeating the step of measuring the output signal with the helicity of the irradiation light turned clockwise and the step of measuring the output signal with the helicity of the circularly polarized light pumping irradiation light turned counterclockwise 100 times. After being obtained, the measurement data was amplified by a preamplifier, counted using a counter board, and processed by a computer to calculate scattered ion intensity I _{↑ (integrated value)} and scattered ion intensity I _{↓ (integrated value)} . .

Next, the scattered ion intensity I _{↑ (integrated value)} , the scattered ion intensity I _{↓ (integrated value),} and the incident He ⁺ ion beam spin polarization rate P _{He + (INPUT)} defined by Expression (2) are _expressed by Expression (1 _). ).
The spin asymmetry A _{(He +, M, 1.4} to _{1.7, 0, 30, 150)} was calculated as a function of the kinetic energy of the scattered ions. M is a target material of any one of Si, Cu, Zn, Ag, Sn, Au, Pb, and Bi.

Next, without using the optical pumping method, an ion beam composed of unpolarized He ⁺ ions is transported to a spin polarizer installed in the vacuum chamber using a beam line, and the spin polarization in the vacuum chamber is performed. The output signal of the spin-polarized He ⁺ ion (scattered ion intensity I _(integrated) is the same as in the case where the helicity of the circularly polarized light pumping irradiation light is clockwise, except that the target of various materials in the chamber is irradiated. _{The value)} ) was measured for 1000 seconds with a secondary electron multiplier placed at the bottom of the electrostatic analyzer.
Thereby, the ISS spectrum at the time of using the target of various materials was obtained.

ISS spectrum using the target of various materials, spin asymmetry factor _{A (He +, M, 1.4~1.7,0,30,150} ) because the corresponding a, spin asymmetry ratio in each peak value _{A ( He +, M, 1.4} to _{1.7, 0, 30, 150)} , the spin polarization _{PHE + (OUTPUT)} was obtained.

FIG. 6 is a graph showing the relationship between the spin polarization rate P _{He + (OUTPUT)} and the atomic number of the target material.
There was a tendency for the absolute value of the spin polarization to increase as the atomic number of the target element increased. This indicates that an element with a higher atomic number should be targeted in order to obtain a higher spin polarization. The maximum spin polarization (about 7%) was obtained in the sample measured when Au was targeted.

(Example 3)
<About incident energy dependency>
The step of measuring the output signal with the helicity of the circularly polarized light pumping irradiation light turned clockwise as in Example 1 except that the incident energy was set to 450, 610, 750, 950, 1050, 1250, 1550, 1670 eV. And the step of measuring the output signal by turning the helicity of the circularly polarized light pumping irradiation light counterclockwise is repeated 100 times alternately to obtain each measurement data, and then the measurement data is amplified by a preamplifier, and then the counter Counting was performed using a board, and processing was carried out by a computer to calculate scattered ion intensity I _{↑ (integrated value)} and scattered ion intensity I _{↓ (integrated value)} .

Next, the scattered ion intensity I _{↑ (integrated value)} , the scattered ion intensity I _{↓ (integrated value),} and the incident He ⁺ ion beam spin polarization rate P _{He + (INPUT)} defined by Expression (2) are _expressed by Expression (1 _). ).
The spin asymmetry A _{(He +, Au, E, 0, 30, 150)} was calculated as a function of the kinetic energy of the scattered ions. The incident energy value E is one of 450, 610, 750, 950, 1050, 1250, 1550, and 1670 eV.

Next, without using the optical pumping method, an ion beam composed of unpolarized He ⁺ ions is transported to a spin polarizer installed in the vacuum chamber using a beam line, and the spin polarization in the vacuum chamber is performed. The output signal of the spin-polarized He ⁺ ion (scattered ion intensity I _{(integrated value)} ) is the same as in the case of “clockwise helicity of circularly polarized light pumping irradiation light” except that the target in the vessel is irradiated Was measured with a secondary electron multiplier installed at the bottom of the electrostatic analyzer for 1000 seconds.
As a result, an ISS spectrum was obtained when the incident energy E was any one of 450, 610, 750, 950, 1050, 1250, 1550, and 1670 eV.

The ISS spectra spin asymmetry factor _{A (He +, Au, E} , 0,30,150) because the corresponding a, a spin asymmetry factor _A at each peak value _{(He +, Au, E,} 0,30,150), A spin polarization PHe _{+ (OUTPUT)} was obtained.

FIG. 7 is a graph showing the relationship between the spin polarization rate P _{He + (OUTPUT)} and the incident energy. The spin polarization P _{He + (OUTPUT)} monotonously decreased with increasing incident energy. As a result, it was shown that in order to obtain a higher spin polarization with a larger absolute value, the incident energy should be higher. In the measured range, the maximum spin polarization rate P _{He + (OUTPUT)} (about 8%) was obtained when the incident energy was 1.67 keV.

Example 4
<About scattering angle dependency>
(4-1)
Example 1 except that a polycrystalline gold thin plate was used as the target, the incident energy was 1.57 keV, the incident angle and the outgoing angle were made equal, and the scattering angle θ was changed in the range of 10 ° to 150 °. Then, the step of measuring the output signal by turning the helicity of the circularly polarized light pumping irradiation light clockwise and the step of measuring the output signal by turning the helicity of the circularly polarized light pumping irradiation light counterclockwise 100 are alternately performed. After each measurement data is obtained repeatedly, the measurement data is amplified by a preamplifier, counted using a counter board, processed by a computer, and scattered ion intensity I _{↑ (integrated value)} and scattered ion intensity I _{↓ (integrated value)} was calculated.

Next, the scattered ion intensity I _{↑ (integrated value)} , the scattered ion intensity I _{↓ (integrated value),} and the incident He ⁺ ion beam spin polarization rate P _{He + (INPUT)} defined by Expression (2) are _expressed by Expression (1 _). ).
The spin asymmetry A _{(He +, Au, 1.57, α = β, θ)} was calculated as a function of the kinetic energy of the scattered ions.

Next, without using the optical pumping method, an ion beam composed of unpolarized He ⁺ ions is transported to a spin polarizer installed in the vacuum chamber using a beam line, and the spin polarization in the vacuum chamber is performed. The output signal of the spin-polarized He ⁺ ion (scattered ion intensity I _{(integrated value)} ) is the same as in the case of “clockwise helicity of circularly polarized light pumping irradiation light” except that the target in the vessel is irradiated Was measured with a secondary electron multiplier installed at the bottom of the electrostatic analyzer for 1000 seconds.
Thus, an ISS spectrum was obtained when a polycrystalline gold thin plate was used as a target, the incident energy was 1.57 keV, the incident angle and the outgoing angle were made equal, and the scattering angle was changed.

Since the ISS spectrum corresponds to the spin asymmetry A _{(He +, Au, 1.57, α = β, θ)} , the spin asymmetry A _{(He +, Au, 1.57, α = β, From (θ)} , the spin polarization rate P _{He + (OUTPUT)} was obtained.

(4-2)
Example 1 except that a polycrystalline lead thin plate was used as the target, the incident energy was 1.57 keV, the incident angle and the outgoing angle were made equal, and the scattering angle θ was changed in the range of 10 ° to 150 °. Then, the step of measuring the output signal by turning the helicity of the circularly polarized light pumping irradiation light clockwise and the step of measuring the output signal by turning the helicity of the circularly polarized light pumping irradiation light counterclockwise 100 are alternately performed. After each measurement data is obtained repeatedly, the measurement data is amplified by a preamplifier, counted using a counter board, processed by a computer, and scattered ion intensity I _{↑ (integrated value)} and scattered ion intensity I _{↓ (integrated value)} was calculated.

Next, the scattered ion intensity I _{↑ (integrated value)} , the scattered ion intensity I _{↓ (integrated value),} and the incident He ⁺ ion beam spin polarization rate P _{He + (INPUT)} defined by Expression (2) are _expressed by Expression (1 _). ).
The spin asymmetry A _{(He +, Pb, 1.57, α = β, θ)} was calculated as a function of the kinetic energy of the scattered ions.

Next, without using the optical pumping method, an ion beam composed of unpolarized He ⁺ ions is transported to a spin polarizer installed in the vacuum chamber using a beam line, and the spin polarization in the vacuum chamber is performed. The output signal of the spin-polarized He ⁺ ion (scattered ion intensity I _{(integrated value)} ) is the same as in the case of “clockwise helicity of circularly polarized light pumping irradiation light” except that the target in the vessel is irradiated Was measured with a secondary electron multiplier installed at the bottom of the electrostatic analyzer for 1000 seconds.
Thus, an ISS spectrum was obtained when a polycrystalline lead thin plate was used as the target, the incident energy was 1.57 keV, the incident angle was equal to the outgoing angle, and the scattering angle was changed.

Since the ISS spectrum corresponds to the spin asymmetry A _{(He +, Pb, 1.57, α = β, θ)} , the spin asymmetry A _{(He +, Pb, 1.57, α = β, From (θ)} , the spin polarization rate P _{He + (OUTPUT)} was obtained.

FIG. 8 is a graph showing the relationship between the spin polarization rate P _{He + (OUTPUT)} and the scattering angle θ.
When the target was gold, the absolute value of the spin polarization rate P _{He + (OUTPUT)} was 8% at the maximum when the scattering angle θ was 140 °.
On the other hand, when the target was lead, the absolute value of the spin polarization rate P _{He + (OUTPUT)} reached a maximum value of 25% when the scattering angle θ = 70 °.
As described above, the scattering angle θ at which the spin polarization rate P _{He + (OUTPUT)} having the maximum absolute value is obtained differs depending on the type of the target element. However, the spin polarization rate P _{He + (OUTPUT)} did not depend on the incident angle α and the outgoing angle β. Further, the spin polarization rate P _{He + (OUTPUT)} did not depend on the crystallinity of the target.

The present invention relates to an electron spin-polarized ion beam generation method and an apparatus for generating the same, and generates an electron spin-polarized ion beam having a spin polarization rate similar to that of the optical pumping method without using the optical pumping method. Can be used in the analytical equipment industry and the like.

DESCRIPTION OF SYMBOLS 1 ... RF discharge tube (ion beam generating part), 2 ... Noble gas element gas introduction port, 3 ... Noble gas element gas exhaust port, 4 ... Optical pumping irradiation light (linearly polarized light), 5 ... Optical pumping irradiation light (circularly polarized light) ), 6 ... Beam line, 7 ... Beam line exhaust port, 8 ... Beam line exhaust port, 9 ... Target manipulator (rotation control mechanism), 10 ... Vacuum chamber, 11 ... (For magnetic field correction) 3-axis coil, 12 ... Target , 13: Electrostatic analyzer, 13a: First analyzer structure, 13a1, 13a2 (electric field application) member, 13c1: Tube, 13c1a: Opening, 13c2b: Opening, 13b: Second analyzer structure, 13b1, 13b2 ... (electric field application) member, 13c2 ... cylindrical part, 14 ... spin polarizer, 15 ... secondary electron multiplier, 51 ... electron spin polarized ion beam generator, g ... rotating shaft.

Claims (12)

Generating an ion beam composed of rare gas element ions;
Making the ion beam incident on one surface of the target and emitting a scattered ion beam;
Capturing the scattered ion beam in an electrostatic analyzer and applying an electric field to generate an electron spin-polarized ion beam, and an electron spin-polarized ion beam generation method comprising:
When the ion beam is incident on one surface of the target, the direction of the magnetic field is 80 ° or more and 100 ° or less with respect to the scattering surface including both the incident direction of the ion beam and the emitting direction of the scattered ion beam. as electron spin polarized ion beam generator and wherein applying a magnetic field to said target.   2. The electron spin polarized ion beam generating method according to claim 1, wherein rare gas element ions are generated by a plasma method.   The method of generating an electron spin polarized ion beam according to claim 1 or 2, wherein the rare gas element is He. The incident energy of the ion beam is at 3 0ke V less than 1 keV, the scattering angle is 0.99 °, electrons according to claim 1, wherein the incident angle is 0 ° Spin-polarized ion beam generation method.   5. The electron spin polarized ion beam generation method according to claim 4, wherein the incident angle is 0 °, and the target includes one material selected from an element group having an atomic number of 50 or more.   6. The method of generating an electron spin polarized ion beam according to claim 5, wherein the target has one material selected from the group consisting of Sn, Au, Pb, and Bi. The ion beam has an incident energy of 1.57 keV, a scattering angle in the range of 60 ° to 90 ° or 110 ° to 150 °, and an incident angle of (180 ° −scattering angle) / 2. 2. The electron spin polarized ion beam generation method according to claim 1, wherein the target is Au. The incident energy of the ion beam is 1.57 keV, the scattering angle is in the range of 25 ° to 140 °, the incident angle is (180 ° −scattering angle) / 2, and the target is Pb. The method of generating an electron spin polarized ion beam according to claim 1 .   Having a step of measuring the spin asymmetry rate of an electron spin-polarized ion beam by the optical pumping method with the same kind of rare gas element, kind of target material, incident energy value, incident angle, exit angle, and scattering angle. The method of generating an electron spin polarized ion beam according to any one of claims 1 to 8. A vacuum chamber, an ion beam generator, a beam line connecting the vacuum chamber and the ion beam generator, and a triaxial coil disposed so as to surround the vacuum chamber, the ion beam generator and the beam line; An electron spin polarized ion beam generator comprising:
A substantially plate-like target and an electrostatic analyzer are arranged in the vacuum chamber,
The target can be rotated around a rotation axis parallel to one surface of the target by a rotation control mechanism,
The electrostatic analyzer is capable of rotating around a rotation axis of the target by a movement control mechanism,
By adjusting the current flowing through the three-axis coil, a magnetic field can be applied to the target .
The triaxial coil has both a magnetic field direction in which an ion beam generated from the ion beam generator is incident on the target and an emission direction in which the ion beam scattered by the target is emitted. versus the scattering plane containing, as a direction of 80 ° to 100 °, the electron spin polarization ion beam generator, wherein the applying child a magnetic field to said target.   11. The electrostatic analyzer includes a cylindrical portion and an electric field applying member arranged so as to surround the cylindrical portion, and an electric field can be applied to the ion beam in the cylindrical portion. Electron spin polarized ion beam generator. The electron spin polarized ion beam generator according to claim 10 or 11, wherein the ion beam generator is an RF discharge tube connected to a rare gas element gas introduction tube.