JPH045587A - High-sensitivity magnetic field detector - Google Patents

Abstract

PURPOSE:To make a detection coil hardly lose detecting balance in extremely weak magnetic field by providing plural detection coils formed of thin films which come into superconducting contact with an input coil and using a means which puts the detection coils in mutual superconducting contact. CONSTITUTION:The one-chip united thin film type SQUID element of a DC type superconducting loop 1 including two Nb/Al2O3/Nb Josephson junctions 8 and the input coil 2 is manufactured by plural processes of sputtering and photolithography. Lead indium coated wires 4 are used as connection lines of the thin film type SQUID element for the detection coils 7 and connected at a connection part 3. The coated wires 4 are wired in a column 5 made of a 'Bakelite(R)' plate. Then four Si substrates 6 which have niobium detection coil loops at upper parts with specific width are incorporated in the opposite side of the column 5 and counter-boring is carried out in the flanks so as to connect the respective loops to the coated wires, thus wiring the lead coated wires. Consequently, the detection coils are difficult to lose the extremely fine magnetic field detection balance and the high-sensitivity magnetic field detector which is easily manufactured and can be mass-produced is obtained.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is directed to a direct current driven superconducting quantum interference device (abbreviated as DCSuperconducting) which is applied to a highly sensitive magnetic detector, a current needle, a displacement meter, a high frequency signal amplifier, etc. Regarding the application of ).

[Summary of the invention]

This invention uses a plurality of detection coils formed of thin films that make superconducting contact with the input coil in a high-sensitivity magnetic field detector that includes a superconducting loop and an input coil that is transformer-coupled to the superconducting loop. The purpose of the present invention is to obtain a highly sensitive magnetic field detector that is easy to manufacture because the contact causes the weak magnetic field detection balance to be disrupted.

[Conventional technology]

Conventionally, as shown in FIG. 4, a superconducting coil 1 and an input coil 2 are transformer-coupled, and a detection coil 10 connected to the input coil 2 is of a bobbin type made of niobium (Nb) wire.
The detection coil 10 and the input coil 2 have been connected by soldering or the like.

[Problem to be solved by the invention]

However, in conventional high-sensitivity magnetic field detectors, niobium (Nb)
Because the wire has a large elastic modulus, its ends tend to become sharp, which causes problems with the magnetic field detection balance and makes it difficult to manufacture.

SUMMARY OF THE INVENTION In order to solve these conventional problems, it is an object of the present invention to provide a high-sensitivity magnetic field detector that is easy to manufacture and that does not cause imbalance in weak magnetic field detection.

[Means to solve the problem]

In order to solve the above problems, the present invention provides a highly sensitive magnetic field detector having a superconducting loop and an input coil transformer-coupled to the superconducting loop. In addition, the detection coils are configured to have superconducting contact with each other, so that the supermagnetic field detection balance of the detection coils can be maintained and manufacturing efficiency can be improved.

[Effect]

In the high-sensitivity magnetic field detector configured as above, the weak magnetic field to be measured is! Detected by the membrane type detection coil, a current is generated in the detection coil, and this current
The weak magnetic field can be measured by transmitting the measuring magnetic field to the input coil through the bIn) wire and to the superconducting loop with which the input coil is transformer-coupled.

That is, since the detection coil is formed of a thin film, it is possible to make the shape and dimensions of each detection coil uniform, and it is possible to perform weak magnetic field measurement with good detection balance.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

FIG. 1 shows a schematic diagram of a highly sensitive magnetic field detector according to an embodiment of the present invention. Nb/AIJ3/Nb (film thickness Nb.

1100n,,A1zO3i 0.5nm) DC type superconducting loop 1 including two Josephson junctions 8 and input coil 2 1 chip 6II 1m square integral thin film type 5QLIID
The device is manufactured using multiple steps including sputtering and photolithography.

The connection wire between the thin film type 5QUID element and the detection coil 7 is coated with lead indium (PbIn)! 4 (diameter 3 mm) and connect at the connecting part 3. Lead indium (PbIn) coated wire 4 A baked plate cylinder 5 with a diameter of 10 mm+ and a length of 40 n+n
is wired inside. At the opposite end of the connection part 3 of this cylinder 5, four 10 mm square, 2 mm thick Si substrates 6 each having a niobium (set to 1100 nm by sputtering) detection coil loop 7 with a width of 100 μm on the top are installed, and at the same time each detection To connect the coil loop and the lead indium (PbIn) coated wire, make a hole on the side and connect the lead indium (PbIn) coated wire.
in) Wire the covered wire. FIG. 2 is a perspective view of the detection coil. In Figure 2, the S of the 101-square, 2m-thick end
A 2111m loop 7 with a radius of 100 μm is installed on the
b (set to 1100n with spuff'/). In this embodiment, in order to constitute a second-order differential gradiometer type detection coil, a lead indium (PbIn) coated wire 4 and four detection coil loops 17 are connected as shown in FIG.

In addition, to further prevent magnetic flux leakage, lead indium (P)
bIn) The covered wire 4 is a twisted wire as shown in FIG. In addition, in cases other than the second derivative (Magne 7) meter,
Although the structure of the present invention can also be applied to a first-order differential system, a third-order or higher-order differential system, etc., detailed explanation will be omitted.

〔Effect of the invention〕

Since the present invention is configured as described above, it produces the effects described below.

By using a means having a plurality of detection coils formed of thin films that make superconducting contact with the input coil, and a means that makes superconducting contact between the detection coils, it is possible to prevent the weak magnetic field detection balance in the detection coils from being disrupted, and to create a This has the effect of making it possible to create a highly sensitive magnetic field detector that can be easily mass-produced.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a high-sensitivity magnetic field detector according to an embodiment of the present invention;
FIG. 2 is a perspective view of the detection coil, FIG. 3 is an explanatory diagram of the lead indium (PbIn) coated wire inside the beta plate, and FIG. 4 is a schematic diagram of a conventional high-sensitivity magnetic field detector. 1... Superconducting loop 2... Input coil 3... Junction, lead indium (PbIn) coated wire, baked plate, Si substrate, detection coil, Josephson junction, connection between detection coil and lead wire PbIn coating Applicant Seiko Electronics Co., Ltd. Agent Patent attorney Takayuki Hayashi Sukehisa 3 Figure 4r2J

Claims (2)

[Claims] (1) A high-sensitivity magnetic field detector having a superconducting loop, an input coil transformer-coupled to the superconducting loop, and at least one detection coil, wherein the detection coil is formed of a thin film, and the input coil and the detection coil are formed by thinning. A highly sensitive magnetic field detector characterized by each connection part of the coil being a superconducting contact. (2) The high-sensitivity magnetic field detector according to claim 1, wherein each of the connecting portions is connected by a lead indium (PbIn) wire.