JP4092396B2 - Magnetization measuring device using helium-3 refrigerator - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a magnetization measuring apparatus necessary for studying physical properties of various substances at cryogenic temperatures, and in particular, uses MPMS that can generate a cryogenic temperature of about 1.8 K using helium 4 conventionally. Furthermore, the present invention relates to a magnetization measuring apparatus using a helium 3 refrigerator, which uses helium 3 and generates a cryogenic temperature up to 0.3K by simply adding a simple device, and can easily perform desired magnetization measurement. .
[0002]
[Prior art]
Magnetization measurement is an indispensable means for studying various physical properties such as magnetic materials and superconductors. Currently, this magnetization measurement is based on MPMS (Magnetic Property Measurement System) of Quantum Design, USA. A measuring device (trade name, the same applies hereinafter) is widely used as a de facto standard measuring device.
[0003]
The upper limit of the measured temperature of this MPMS reaches 800K by introducing the high temperature option, but the lower limit remains at 1.8K due to the decompression of the liquid helium 4. Therefore, the magnetization measurement is being conducted in the research of special superconductors such as Ru-based and Re-based superconducting oxides and various heavy electron-based superconductors that have attracted attention in recent years. Is not possible with this MPMS. As an example of a magnetic material, pNPNN, the world's first pure organic ferromagnet, had a ferromagnetic transition temperature of 0.6 K, so research was conducted with a handmade device.
[0004]
[Problems to be solved by the invention]
As described above, the temperature of MPMS, which has been widely used in the past, can only be lowered to about 1.8 K, and as described above, it has not been possible to measure the magnetization of various substances that have been attracting attention in recent years. Therefore, it is necessary to create a device that can perform magnetization measurement at 1.8K or less, but in that case, it becomes a so-called custom-made product, so it must be very expensive and not versatile. Therefore, it is difficult to use the created device in a wide range of fields.
[0005]
In addition, it is extremely difficult to configure such a custom-made device so as to be able to measure DC magnetization using a superconducting interference element (SQUID), and it is only possible to measure AC magnetization. However, such AC magnetization measurement has low sensitivity, and the magnitude of magnetization cannot be determined directly. Furthermore, even when measuring DC magnetization, old measurement methods such as the extraction method, vibration sample method, and magnetic field insertion method were used, and measurement could not be performed using the ultra-sensitive SQUID. . For this reason, the benefits of ultra-high sensitivity obtained by using the SQUID as described above cannot be obtained.
[0006]
Therefore, the present invention can generate a cryogenic temperature of about 0.3 K by simply adding a simple means to the conventional MPMS (Magnetic Property Measurement System), It is a main object to provide a magnetization measuring apparatus using a helium 3 refrigerator capable of measuring the magnetization characteristics with high sensitivity at the extremely low temperature.
[0007]
[Means for Solving the Problems]
The present invention has developed an apparatus capable of measuring magnetization at a cryogenic temperature of up to 0.3K by utilizing MPMS as a commercially available magnetization measuring apparatus that is currently widely used in light of the above-described present situation. Is. In addition, by using this apparatus in combination with the technique disclosed in Japanese Patent Application No. 2001-353149, which is the previous invention by the present inventor, the electrical resistance and Hall effect measurement up to 0.3K can be performed. Is.
[0008]
The basic idea of the present invention is that the 1.8K space provided by MPMS is lowered to 1.5K by an auxiliary rotary pump, and a small helium 3 refrigerator that can be moved up and down is inserted into the space. The DC magnetization is measured by moving up and down in the pickup coil. The helium 3 refrigerator can reduce the temperature of the sample to 0.3K. By moving the entire refrigerator up and down, the sample temperature can be kept constant, unlike the case where only the sample is moved up and down in the liquefied helium 3. The present invention adopts the following configuration in order to solve the above-described problems based on the basic technical idea as described above.
[0009]
That is, the invention according to claim 1 is a helium 3 refrigerator equipped with a sample rod on which a sample is fixed, and a main pipe which is mounted with the sample rod and forms a space for cooling with helium 3 around the sample rod. When a cylindrical body in which the helium 3 refrigerator is to be inserted, provided with a cooling means according to helium 4 in the cylindrical body periphery, superconducting magnet, the magnetic field forming means, temperature control means, and a SQUID device having a magnetic field adjustment means A helium 3 refrigerator is inserted into a cylinder of the magnetization measuring device having the SQUID element as a detector, and the sample rod is attached to a main pipe of the helium 3 refrigerator. This is a magnetization measuring device using a helium 3 refrigerator.
[0010]
In the invention, the primary pipe is communicated with the outside of the helium-3 supply device and base rose, the helium 3 refrigerator box for keeping the space of the movable range of the bellows airtight according to claim 2 When a lower end opening provided to mount the box in an airtight state to the cylindrical body, and a said main pipe, Rutotomoni and a temperature measuring means and temperature varying means to the sample rod, the temperature measuring means And a temperature variable means and an external control device are connected by a signal line .
[0011]
The invention according to claim 3 is characterized in that the cooling means by the helium 4 is provided with an auxiliary pump provided separately from the main pump for the magnetization measuring device using the SQUID element as a detector. The described helium-3 freezer-based magnetization measurement device.
[0012]
Further, the invention includes a magnetization measuring device according to the detector the SQUID element and the helium 3 refrigerator, connected to the sample rod, the magnetic field of the magnetization measuring apparatus for a detector of the SQUID element according to claim 4 control and a sample temperature control by a heater provided in the magnetization measuring device and helium 3 refrigerator and samples rod and detector the SQUID element, for magnetization measuring device for controlling the magnetization measurement operation of the sample provided to the sample rod 2. A magnetization measuring apparatus using a helium 3 refrigerator according to claim 1 , further comprising a control device.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram schematically showing the structure of a magnetization measuring apparatus using a helium 3 refrigerator according to the present invention and a software configuration of a control apparatus for a magnetization measuring apparatus. The basic configuration of the magnetization measuring apparatus using the helium 3 refrigerator shown in FIG. 1 uses the magnetization measuring apparatus 1 that uses the main components of an apparatus that has been widely used conventionally as MPMS as described above. In this apparatus, a helium 3 refrigeration apparatus 20 as will be described later can be attached to an internal liquid helium container 2 through an upper opening, and this helium 3 refrigeration apparatus 20 has been conventionally used for MPMS. Similarly, the sample rod 5 can be mounted.
[0014]
The basic function of the magnetization measuring apparatus 1 as a measuring apparatus is that a micro magnetic field generated by a magnetic sample fixed to the sample rod 5 can be detected by a SQUID element applying the Josephson effect of a superconductor. Therefore, it is possible to measure the magnetic susceptibility, the magnetization curve, and the Meissner effect of the superconductor sample.
[0015]
More detailed configurations of the magnetization measuring device 1 and the helium 3 refrigeration device 20 and the like are shown in an exploded view in FIG. 2 and in a schematic diagram in which a part of the configuration is enlarged in FIG. A cylindrical outer cylinder 6 is suspended from the upper opening in the liquid helium container 2 to be accommodated, and the lower end surface of the liquid helium container 2 extends into the liquid helium 4 and opens. A thin tube 7 is provided.
[0016]
The outer cylinder 6 extends to the upper outside of the liquid helium container 2 and is provided with a pump connection opening 19 in a side wall portion thereof. A main pump 9 provided in the conventional MPMS is connected to the pump connection opening 19 by a pipe 10. It is connected. Further, in this apparatus, an auxiliary pump 11 is also connected to the pipe 10 as shown in FIG. 1, and, as will be described later, by operating the auxiliary pump 11 in addition to the operation of the main pump 9, The interior of the chamber 12 can be cooled further.
[0017]
A cylindrical sample chamber cylinder 8 is provided inside the outer cylinder 6, and an end surface 13 is provided at a position away from the opening of the thin tube 7 at the lower end of the sample chamber cylinder 8, and its upper end is the upper end of the outer cylinder 6. The sample mounting opening 14 is formed further upward than the section, and a valve for blocking the measurement space from the atmosphere immediately below it, catching the part where the sample rod is partially thick, and moving the sample rod up and down There is a drive mechanism 33 to be moved. 2C, the lower end opening 17 of the box 16 as shown in FIG. 2B, and a sealing member 18 such as a Wilson seal with good sealing performance. It can be connected. In the Wilson seal, when the screw is tightened, the O-ring can tighten the central pipe to seal the vacuum. The seal portion is not limited to the Wilson seal method, and may be constituted by a flange using an O-ring gasket.
[0018]
As shown in FIG. 2 (a), a sample rod 5 having a plurality of sample pieces, heaters, temperature sensors and other measurement members 21 fixed below is provided on a helium 3 freezer 20 as shown in FIG. 2 (b). By opening the lid 36, it can be inserted into the main pipe 23 through the sample rod mounting opening 24 formed at the upper end of the main pipe 23. When the sample rod 5 is inserted into the main pipe 23 as described above, the seal member 38 such as a Wilson seal provided in the sample rod mounting opening 24 can be sealed with good sealing performance. Yes. In the illustrated embodiment, a heat insulating vacuum member 29 is provided on the outer periphery of the lower portion of the main pipe 23 to insulate the inside of the main pipe 23 from the space of the sample chamber 12 outside thereof.
[0019]
As shown in FIG. 2B or the schematic diagram of FIG. 3, the helium 3 refrigeration apparatus 20 has a bellows 28 between an opening 25 provided in the upper side wall of the main pipe 23 and an opening 27 in the side wall 26 of the box 16. And the gas handling system 30 of helium 3 makes it possible to perform decompression by exhausting the main pipe 23, introducing helium 3 into the main pipe 23, and discharging vaporized helium 3, as will be described later. . The gas handling system 30 of helium 3 and the opening 27 are connected by a pipe 31, and a valve 32 is provided in the middle.
[0020]
Further, in the case where such a helium 3 gas handling system 30 is provided, the main pipe 23 can be moved with respect to the box 16, whereby the box 16 fixed to the outer cylinder 6 of the magnetization measuring device 1 is made. Thus, the main pipe 23 can be moved up and down by the moving device 33, the sample rod 5 is moved up and down at the time of measurement, and an induced electromotive force proportional to the magnetization of the sample is generated in the pickup coil wound around the outer periphery of the outer cylinder 6. , Detected by SQUID.
[0021]
As shown in FIG. 2B, the signal line 34 extends from the side wall 26 of the box 16 to the inside, and when the sample rod 5 is attached to the main pipe 23 as shown in FIGS. Is connected to a connector 35 provided at the upper end of the sample rod 5. Thereby, it is possible to exchange signals with the control device 40 for magnetization measuring apparatus as shown in FIG. The magnetization measuring device 1 can also be connected to the magnetization measuring device control device 40 for the internal magnetic field control and temperature control.
[0022]
As shown in FIG. 1, the magnetization measuring device control device 40 can be operated using MV (Multi-View) software 41 that has already existed as control software for the magnetization measuring device 1, and in the present invention, In order to perform the magnetization measurement of the helium 3 in the temperature range of 0.3 to 2 K using the helium 3 refrigeration apparatus 20, software 42 shown as i-Helium 3 in the figure is further used.
[0023]
The i-Helium 3 software 42 allows direct input / output to / from the sample, temperature sensor, and heater on the sample rod 5, and also allows the magnetization measuring apparatus to perform a predetermined operation. The user performs the measurement basic data input 43 as a measurement operation command in advance. As a result, during the measurement operation, the i-Helium 3 software command activates the MV software 41 through the currently widely used HSP software 44, and the sequence control means of the MV software 41 causes the magnetization measuring device 1 to Magnetic field control, sample magnetization measurement, sample magnetization measurement signal input processing, and the like can be performed.
[0024]
In the magnetization measuring apparatus using a helium 3 refrigerator according to the present invention configured by combining the above-described apparatuses, when the apparatus is used, the members are first disassembled as shown in FIG. As shown in FIG. 2, the sample is mounted on the sample rod 5 to which the temperature sensor and the heater are fixed, the ceiling 36 of the box 16 is opened as shown in FIG. 2B, and the sample rod mounting opening of the main pipe 23 is opened. After being inserted into 24, as shown in FIG. 3, sealing is securely performed by a sealing member 38 such as a Wilson seal at the upper end of the main pipe 23.
[0025]
Thereafter, the connector of the signal line 34 extending into the box 16 is connected to the connector 35 above the sample rod 5. The sample temperature is measured and controlled through the signal line 34. Next, the lid 36 on the ceiling of the box 16 is closed to seal the inside. Thereafter, the inside of the main pipe 23 is preliminarily evacuated by a high vacuum exhaust system via the bellows 28 by the gas handling system 30 of helium 3 shown in FIG. 1, and the valve 32 is closed in this state.
[0026]
Next, the sample space is heated to 300 K using the function of MV software, which is the MPMS control software of the control device 40 for the magnetization measuring apparatus, and the vent valve is opened so that a curtain of helium gas can be produced. FIG. The lid 15 of the uppermost sample mounting opening 14 of the sample chamber cylinder 8 shown in FIG. The main pipe 23 of the helium 3 refrigeration apparatus 20 with the sample rod 5 mounted thereon is inserted into the sample mounting opening 14, and the sample mounting opening 14 and the lower end opening 17 of the box 16 are brought into contact with each other for sealing. Sealed with the member 18. Since the seal member 18 is not sufficiently sealed with a standard MPMS product, it is replaced with a Wilson seal as described above to enhance the seal property.
[0027]
Thereafter, the valve 32 is released, and the main pump 23 is exhausted to a high vacuum by the gas handling system 30 of helium 3, and the main pump is operated by the function of the MV software 41 which is the control software of the MPMS in the control device 40 for the magnetization measuring device. 9 is activated and the sample space is cooled to 1.8K. Here, when the auxiliary pump 11 including a rotary pump is further operated, the temperature of the sample space can be lowered to about 1.5K.
[0028]
In this state, when helium 3 gas ( ³ He gas) is introduced into the main pipe 23 through the liquid nitrogen trap by the operation of the helium 3 gas handling system 30, the helium 3 gas is liquefied and stored below the main pipe 23. . After storing a predetermined amount of liquefied helium 3 gas, the helium 3 gas handling system 30 is operated to evacuate the helium 3 gas in the main pipe 23 using a closed exhaust system, whereby the sample attached to the lower end of the sample rod 5 Can be maintained at a low temperature of 0.3K.
[0029]
Thereafter, data is acquired by the function of the measurement software of MPMS while controlling the temperature and magnetic field of the sample according to the needs of the measurer. In this case, for the magnetization measuring apparatus shown in FIG. Although it can be operated by the software of the control device 40 as described above, a part that cannot be operated by the MV (Multi-View) software 41 used in MPMS has been developed to compensate for this. It can be operated by the software 42 of i-Helium3.
[0030]
i-Helium3 has two functions. One is i) temperature measurement / control of 0.3 to 2K, and the other is ii) indirectly controlling the MV through the HSP and automatically taking the data. Although only the function i) can be measured if the measurer directly operates the MV, it is very inconvenient if a large amount of data is to be taken, so the function ii) was added. That is, the measurer gives instructions for necessary temperature change and magnetic field change to i-Helium 3 at a time. i-Helium3 creates a necessary temperature point by controlling a resistance bridge with a PID temperature control mechanism, and indirectly controls MV via HSP to create a necessary magnetic field. Thereafter, the i-Helium 3 indirectly controls the MV to move the helium 3 refrigerator in which the sample is set up and down to acquire magnetization data.
[0031]
In the magnetic measurement apparatus of the previous application, the computer for controlling the MPMS and the computer for measuring the electric resistance / Hall effect, etc. were different, but in the apparatus shown in the above embodiment, the operating system message is displayed. By publishing method, it can be integrated into one unit, and software for controlling measurement can also be integrated into one unit.
[0032]
The magnetic measuring apparatus using the helium 3 refrigeration apparatus of the present invention having the above structure and operating as described above uses the MPMS that has been widely used in the past, so that the space in the main pipe 23 can be cooled to a temperature as low as 0.3K. In addition to using this as a magnetization measuring device as described above, it can also be used for general purposes, for example, measuring electrical resistance and Hall effect.
[0033]
【The invention's effect】
Since the present invention is configured as described above, it is possible to generate a cryogenic temperature of about 0.3 K by using a widely used MPMS and adding simple means thereto. Under this, physical properties such as magnetization characteristics can be measured with high sensitivity.
[Brief description of the drawings]
FIG. 1 is a system configuration diagram of an embodiment of the present invention.
FIG. 2 is an exploded sectional view of the same embodiment.
FIG. 3 is a schematic diagram of main components of the same embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Magnetization measuring apparatus 2 Liquid helium container 5 Sample rod 6 Outer cylinder 7 Narrow tube 9 Main pump 10 Pipe 11 Auxiliary pump 12 Sample chamber 13 End surface 14 Sample mounting opening 15 Lid 16 Box 17 Lower end opening 18 Seal member 19 Pump connection opening 20 Helium 3 Refrigerating device 21 Measuring member 23 Main pipe 24 Sample rod mounting opening 25 Opening 26 Side wall 27 Opening 28 Bellows 29 Heat insulating vacuum member 30 Gas handling system 31 Pipe 32 Valve 33 Moving device 34 Signal line 35 Connector 40 Magnetization measuring device control device 41 MV software 42 i-Helium3 software 43 Basic data input unit for measurement 44 HSP software

Claims (4)

A sample rod to which the sample is fixed;
A helium 3 refrigerator equipped with a main pipe which is mounted with the sample rod and forms a space for cooling with helium 3 around the sample rod;
A cylindrical body in which the helium 3 refrigerator is to be inserted, provided with a cooling means according to helium 4 in the cylindrical body periphery, superconducting magnet, the magnetic field forming means, temperature control means, and a SQUID device having a magnetic field adjustment means detector and a magnetizing measuring device according to,
Use of the helium 3 refrigerator, wherein the helium 3 refrigerator is inserted into a cylinder of a magnetization measuring device using the SQUID element as a detector, and the sample rod is attached to a main pipe of the helium 3 refrigerator. Magnetization measuring device. It said main pipe is communicated with the outside of the helium-3 supply device and base Rose,
The helium 3 refrigerator includes a box for keeping a space in a movable range of the bellows in an airtight state, a lower end opening provided for mounting the box in an airtight state on the cylindrical body, and the main pipe. ,
Rutotomoni and a temperature measuring means and temperature varying means to the sample rod, the temperature measuring means and helium 3 refrigeration according to claim 1, characterized in that connected by the temperature varying means and an external control device and a signal line Machine-based magnetization measuring device. The helium 3 refrigerator-use magnetization measuring device according to claim 1, wherein the cooling means by the helium 4 includes an auxiliary pump separately provided from the main pump for the magnetization measuring device using the SQUID element as a detector. . A magnetization measuring device according to the detector the SQUID element and the helium 3 refrigerator, connected to the sample rod, and the magnetic field control of the magnetization measuring apparatus for a detector of the SQUID element, a detector the SQUID element wherein the sample temperature control, further comprising: a magnetization measuring device control device for controlling the magnetization measurement operation of the sample provided to the sample rod by the heater provided in the magnetization measuring device and helium 3 refrigerator and samples rod to The helium 3 refrigerator-based magnetization measuring apparatus according to claim 1 .

Images