JP2002006018A - Magnetic field applying device for squid microscope - Google Patents

Abstract

PROBLEM TO BE SOLVED: To measure while applying a magnetic field by locally magnetic- shielding a part of an SQUID sensor winch is especially affected by a magnetic field. SOLUTION: There is provided such a configuration as to measure while applying a magnetic field by locally magnetic-shielding a part of the SQUID sensor which is especially affected by a magnetic field.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scanning type small magnetic field measuring apparatus, and more particularly to a SQUID microscope applied to the evaluation of superconducting materials and magnetic materials, and processed products or functional devices.

[0002]

2. Description of the Related Art FIG. 2 shows a configuration diagram of a conventional SQUID microscope.

The SQUID microscope is configured such that a sample setting table 1 on which a measurement object 5 is set, a scanning stage 2 for moving the sample setting table 1 to XYZ, and a cooling device 3 are cooled to oppose the measurement object 5. It is composed of the SQUID sensor 4 installed. The scanning stage adjusts the position in the Z-axis direction, brings the SQUID sensor 4 close to the measuring object 5, scans the measuring object 5 in the XY plane with the scanning stage, and
The magnetic field distribution on the measurement object 5 generated by the measurement is measured.

[0004]

In the prior art, since the bare SQUID sensor 4 scans the object 5 to be measured, the application of a magnetic field affects the operation of the SQUID sensor 4.
Problems such as deterioration of the S / N of the measurement result and the inability of the SQUID sensor to operate due to magnetism occurred. For this reason, measurement was performed without applying a magnetic field.

[0005]

Therefore, in order to solve the above-mentioned problems, the present invention provides a method for measuring a SQUID sensor while applying a magnetic field by locally magnetically shielding a portion of the SQUID sensor which is particularly affected by a magnetic field. I made it possible.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments corresponding to the first to fifth aspects of the present invention will be described below.

FIG. 1 shows an overall configuration diagram of a measuring apparatus according to a first embodiment of the present invention.

The SQUID microscope according to the present invention comprises a sample setting table 1 on which a measurement object 5 is set, a scanning stage 2 for moving the sample setting table 1 to XYZ, and a cooling device 3 for cooling the measurement object 5. A SQUID sensor 4 installed in opposition to the magnetic shield 6 and a magnetic field applying coil 7 installed to apply a magnetic field to the measurement object 5
It is composed of

FIG. 3 is a schematic diagram showing the structure of the SQUID sensor 4 and the magnetic shield 6. The SQUID sensor 4 is integrated on a rectangular silicon chip 10.
A superconducting ring 9 having a Josephson junction 8 is located at a substantially central portion of the device, and a detection coil 9 is located at a corner portion. The magnetic shield 6 performs measurement while applying a magnetic field to the measurement object 5 with the magnetic field applying coil 7. Then, when this applied magnetic field applies a magnetic field to the Josephson junction 8, the SQUID
The magnetic shield 6 is provided so that no magnetic field is applied to the portion of the superconducting ring 9 and the detection coil 9 goes out of the magnetic shield 6 for measurement.

In such a configuration, the Z axis is driven by the scanning stage 2, and the object 5 to be measured is first brought close to the detection coil 9 of the SQUID sensor 4. Subsequently, a magnetic field is applied to the measurement object 5 by the magnetic field application coil 7. And the scanning stage 2
Scans the measurement area of the measurement object 5 and detects the magnetic distribution of the measurement area with the detection coil 9 outside the magnetic shield 6. At this time, the applied magnetic field is attenuated by the magnetic shield 6 and does not affect the Josephson junction 8. The material of the magnetic shield may be a superconducting material or a high magnetic permeability material such as permalloy.

FIG. 4 shows an overall configuration diagram of a measuring apparatus according to another embodiment of the present invention.

The SQUID microscope according to the present invention has a sample setting table 1 on which a measurement object 5 is set, a scanning stage 2 for moving the sample setting table 1 in XYZ, and a cooling apparatus 3 which is cooled by a cooling device 3 and opposes the measurement object 5. And the first SQUID sensor 11 partially installed in the magnetic shield 6.
And the second SQUI installed entirely inside the magnetic shield 6
A D sensor 12, a magnetic field applying coil 7 installed to apply a magnetic field to the measurement object 5, a compensation magnetic field applying coil 13 to apply a magnetic field to the magnetic shield 6, and a second SQUID
The control device 14 is configured to control a magnetic field generated by the compensation magnetic field application coil 13 according to the output of the sensor 12. The first SQUID sensor 11 is the same as in FIG. 3 of the above-described embodiment, the detection coil is outside the magnetic shield 6, the superconducting ring including the Josephson junction is inside the magnetic shield, and the external Installed so as not to be affected by the magnetic field. The entire second SQUID sensor 12 is installed in the magnetic shield 6. With such a configuration, the first SQUI
The measurement is performed by the D sensor 11. When a magnetic field is applied by the magnetic field applying coil 7 during measurement, the magnetic field is attenuated by the magnetic shield 6 and enters the inside of the magnetic shield 6. The attenuated magnetic field is detected by the second SQUID sensor 12, and its value is taken in by the control device 14, and a magnetic field opposite to the magnetic field applied by the magnetic field applying coil 7 is generated so that the value is minimized. As shown in FIG.
Control 3 This method actively minimizes the magnetic field inside the magnetic shield 6 so that the applied magnetic field does not affect the first SQUID 11.

[0013]

According to the present invention, a magnetic field can be applied so as not to affect the operation of the SQUID, and the characteristics of the object to be measured when the magnetic field is applied can be measured. Thus, there is an effect that a new application such as measurement of a change in a magnetic domain structure of a measurement object in a magnetic field is enabled.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a SQUID microscope according to a conventional technique.

FIG. 3 is a schematic diagram illustrating a configuration of a magnetic shield unit according to a first embodiment of the present invention.

FIG. 4 is a block diagram showing a configuration according to another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Sample setting table 2 Scanning stage 3 Cooling device 4 SQUID sensor 5 Object to be measured 6 Magnetic shield 7 Magnetic field application coil 8 Josephson junction 9 Detection coil 10 Silicon chip 11 First SQUID sensor 12 Second SQUID sensor 13 Compensation magnetic field Applied coil 14 Control device

Continued on the front page (72) Inventor Atsushi Nagata 1-8-1, Nakase, Mihama-ku, Chiba-shi, Chiba Prefecture Inside Seiko Instruments Inc. (72) Inventor Masanori Ikeda 1-8-8, Nakase, Mihama-ku, Chiba-shi, Chiba Seiko Instruments Inc. In-house F term (reference) 2G017 AC01 AD32 2G053 AA11 AA30 AB14 BB05 CA10 DA01 DB02 DB11 DB20 4M113 AC08 AC46 AD36 AD44 AD45

Claims (4)

[Claims] 1. A SQUID microscope comprising a sample setting table on which an object to be measured is installed, a scanning stage, an SQUID sensor, and a cooling device for cooling the SQUID sensor, which are installed so that a magnetic field is applied to the object to be measured. A magnetic field applying coil, and a magnetic shield provided so as to cover a part of the SQUID sensor. 2. The magnetic field applying device for a SQUID microscope according to claim 1, wherein a high magnetic permeability material is used as the magnetic shield. 3. A magnetic field applying apparatus for a SQUID microscope according to claim 1, wherein a superconducting material is used as the magnetic shield. 4. A SQUID microscope comprising a sample setting table on which an object to be measured is installed, a scanning stage, a first SQUID sensor, and a cooling device for cooling the SQUID sensor, wherein a magnetic field is applied to the object to be measured. A magnetic field applying coil, a second SQUID sensor, a magnetic shield installed so as to cover a part of the first SQUID sensor and the entire second SQUID sensor, and near the magnetic shield. A magnetic field applying device for a SQUID microscope, comprising: a magnetic field compensating coil for applying a magnetic field; and a control device for controlling a magnetic field generated by the compensating magnetic field applying coil in accordance with an output of the second SQUID sensor.