JPS59143976A - Magnetostriction measuring apparatus - Google Patents

Abstract

PURPOSE:To measure bend of a sample simply by naked eyes directly or a photography or the like using an ordinary metal microscope by applying an even magnetic field to the sample employing a spherical coil. CONSTITUTION:A winding of a coil is wound so as to have a circular current overlapping at an equal space. A sample chamber is provided inside and an object lens 4 of a microscope is placed from a lens insertion port on the top thereof to observe displacement of a standing sample 2 focusing the end thereof. For a thin film sample, the measurement of magnetostriction is equivalent to measuring bend of a sample and therefore, the sample 2 is formed on a cover glass, a microsheet or the like to make it easy to bend. This enables the application of an even magnetic field to a sample with a small coil because the magnetic field becomes uniform within a spherical coil.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for measuring magnetostriction of thin films.

Conventionally, magnetostriction has been generally measured using a strain gauge using a resistance wire sound, but this method is suitable for use when the sample has a certain If thickness. - In the case of a thin film, the stress exerted by the strain gauge becomes a problem, so Lt cannot be used in this case. In addition, there are methods for measuring magnetostriction of thin film samples, such as methods using an optical lever and methods using volume/gravity changes, but the optical lever method requires a large space because the displacement is fully expanded.

The present invention has been made in view of the above, and its purpose is to easily measure magnetostriction using an ordinary metal microscope.

Since a base plate is always required to create a thin film, the distortion of the magnetic body is detected as the warpage of the entire body including the base plate. Therefore, for thin film samples, measuring magnetostriction is equivalent to measuring the warpage of the sample. Therefore, an apparatus for measuring the warpage of a sample directly with the naked eye or with a photocoat is shown below.

In order to suppress θ-induced distortion, it is essential to deter flies, and it is desirable to apply a uniform magnetic field to the sample. When a magnetic field f is generated using a Helmholtz coil or the like, the distance between the microscope's sharp tube and the sample stage is relatively narrow, and it is difficult to install a Helmholtz coil of sufficient size. In addition, if the microscope is turned on while the microscope is in use, for example, if the microscope is placed inside a Helmholtz coil, it will become difficult to operate the microscope.

Therefore, the present invention solves all of the above problems by using a spherical coil as the magnetic field generating coil.

A spherical coil is a spherical coil with coiled wire. In other words, it can be thought of as a spherical stack of circular currents with different diameters.

Figure 1 shows the situation. Assuming that the coil is wound into a spherical shape with n stages and a current is passed through the coil, one circular current corresponds to a magnetic moment of m-μO S. μoU vacuum permeability, S
is the area encompassed by the 15th school day. If the diameter of the sphere formed by the coil is fcfl, one circular current r, the thickness R/
It is thought that a magnetic field equivalent to a circular magnetic plate with a circular current at the edge is created at n. Figure 2 shows its appearance. If the magnetization of the magnet is M, it is expressed as follows. Since the electric current is constant, it can be considered as n stacks of uniformly melted circular magnetic plates.n
If (r, -) is sufficiently large, then the spherical coil is equivalent to a uniformly magnetized magnetic sphere. Although the magnetic fields are different, the magnetic flux density is continuous, so if the external magnetic field is equal, the internal magnetic flux density is the same for the magnet ball and the spherical coil.

The fact that the magnetic field inside a ferromagnetic material is uniform can be proven as follows. Unit volume alc! Assume that a sphere has magnetic poles of density J Q, ITI and -q m, and that this sphere is placed on the market with a displacement of d as shown in Fig. 6.

Each location has a magnetic moment of M=qm11d. The magnetic field at a position r from the center of a sphere with a density of +qll H+ (r) H+(r)=(
qm/6μo)・r, and the 68th place Vm+ is VB+ = S H+(r)dr = (-qm/6・μ0)・r2 If you do the same for −C for a sphere with a density of -qm, then Vm
-= (qrn/6μo)-r2-4- q m sphere'
When stacking jc-qm spheres with a shift of d, the grinding position Vm at the position of d is (assuming the shifted direction is kx direction), so I Therefore, the magnetic field Hx is 7″L, which includes the position variable. Therefore, the internal magnetic field is constant.The magnetic flux density inside this magnetic sphere is B-μ
o H-1-M Since H and M are independent of location, B has a constant value internally. In the spherical coil, the i1σ of H is different, but B is the same, so the magnetic field H' in the spherical coil is constant from B=-μ, H'.

In this way, the flB field becomes uniform within the spherical coil, so it is possible to apply a -(axe field) to the sample using a small coil.In reality, an insertion port for the objective lens is required. Therefore, although it is not perfect, it can be resolved by changing the way the coil is wound near the lens insertion port.

i fc As is clear from the above proof, the coil is wound in such a way that circles IF/-currents are stacked at equal intervals, as shown in FIG. Then, as shown in Fig. 4, a sample chamber is set up inside, the objective lens of the microscope is inserted through the lens insertion opening in the base part, and the entire focus is placed on the end of the sample that is erected as shown in (2). Observe. In order to fix the sample on the sample stage, it is necessary to split the coil as shown in Figure 5, but by using the split type, the distance between the sample stage and the lens barrel in the microscope theory is narrow. It is also possible to completely fix the coil.

The measurements are carried out as shown in FIG. The sample is formed into a cover glass, microsort, etc. so that it is easily warped.

In addition, when a current is passed through the coil, the heat generated by the coil deforms the coil shape and prevents it from affecting observation.
, W), as shown in FIG. 4, the sample stage and coil are separated.

The maximum magnification of a microscope is usually about 1000 times, and it is only possible to confirm it with the naked eye (rJ' 0.2 micrometer warpage?), but it is possible to increase the resolution a little more by using photographs. It is.

As described above, by using the magnetostriction measuring device according to the present invention, it is possible to easily measure magnetostriction. In particular, the comparison of the magnitude of magnetostriction, 1 negative 1'I]
This can be done very easily.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a spherical coil. (1) Cut-out plate stone Figure 3 (1) + qm magnetization block / ζ sphere (2) - qm magnetization block Figure 4 (Figure 4 is a layout diagram of the spherical coil and sample chamber. 1) Coil type (2) Sample (6) Sample stand (4) Objective lens (5) Coil stand Figure 5 is an example of dividing the coil type. Figure 6 shows how a spherical coil is installed in the microscope. (1) Spherical coil (2) Metallic microscope (3) Photographer, (4) Power supply unit Figure 4 Figure 5 Li ;,,, rS Figure 6 Procedural amendment (method) 1 Indication of the case 11β Japanese 58 years Patent application No. 1B455 x 2 Name of the invention Magnetostriction measuring device 3 Person who applies forward pressure Representative director Hisashi Nakamura也4 Representative 8, Procedure for following the attached sheet of lottery contents Amendment book (method) % formula % A meeting called ``Brown 5 Diagram'', [Figure 3 is +qm, '11'' im I bi 1 This is a diagram showing a virtual sphere.

Claims (1)

[Claims] In the magnetostriction measurement device of Thin Film Test)-1, nine temples were equipped with a spherical coil that applied a magnetic field to the sample, a sample fixing stage installed near the center of the nuclear spherical coil, and a microscope lever to detect minute changes. Magnetostriction measuring device used for this purpose.