Hitachi, Ltd.

Other

Research Development Corporation of Japan

Rikagaku Kenkyusko

Hideaki Nakane

Mutsuko Hatano

Toshikazu Nishino

Haruhiro Hasegawa

Etsuji Yamamoto

Ushio Kawabe

Eiichi Goto

Koichi Yokosawa

Masao Yabusaki

Yukiko Ogura

Shigeru Matsui

Hideki Kohno

Kazumasa Takagi

Yutaka Harada

Toshiyuki Aida

Kazuo Saitoh

Tokuumi Fukazawa

Yoshinobu Tarutani

Mitsuo Suga

Nobuo Miyamoto

Takashi Onodera

Juan C Cubillos

A superconducting device low in power dissipation and high in operating speed is fabricated by use of a combination of a superconductor material and a semiconductor material. The superconducting device having a low power dissipation and high operating speed characteristic according to the present invention is suitable for configuring a large-scale integrated circuit.

Superconducting device

An oxide superconducting device has a junction structure composed of at least one oxide superconductor and at least one insulator in which carriers have been generated. As the insulator in which carriers have been generated, there can be used, for example, SrTiO.sub.3 doped with Nb. With such a device, rectifying characteristics can be attained in the junction.

Oxide superconducting device

A high-sensitive magnetometer has two SQUIDs each comprising a superconducting loop with one or more Josephson junctions and also has a coil comprising a continuous loop for providing magnetic flux of input signals to each of the SQUIDs in opposite directions. The magnetic flux of the input signals is detected by sums of output voltages of the SQUIDs. Magnetic flux noises equally applied on the two SQUID are cancelled by the continuous loop and at addition of the output voltages of the SQUIDs, thus large output signals can be obtained because sums of the two SQUID output signals are obtained.

Noise canceling high-sensitive magnetometer

Since a superconducting quantum interference device (SQUID) using a high temperature superconductor operates at the liquid nitrogen temperature 77 K, which is higher than the liquid helium temperature 4.2 K, it is necessary that the value of signal voltages is at a level, which is sufficiently higher than the thermal noise level. The superconducting inductance L should be decreased with increasing current flowing through Josephson junctions in the SQUID. The superconducting inductance can be reduced by various methods such as reduction in the size of the aperture of the superconducting inductance, parallel connection of superconducting inductances, utilization of a superconducting ground plane, etc., in order to realize a SQUID, which can be use in a wide application field at the liquid nitrogen temperature 77 K.

Superconductive quantum interference device in high temperature

A pickup coil and a planar type SQUID are formed integrally on a single substrate to form a SQUID magnetometer. The SQUID is disposed on the surface of a projecting portion of the substrate and an insulating layer for spacing is laminated on the SQUID. The top, bottom and side surfaces of the assembly of the SQUID and insulating layer covering the same are all covered with a superconducting layer to form a magnetic shield for enclosing the SQUID. The magnetic shield is remote from the planar type pickup coil disposed on the remaining portion of the substrate by a distance which is equal to or greater than a length of one side of the size of the magnetic shield, thereby preventing magnetic flux distortion due to the presence of the magnetic shield from disturbing coil balance of the pickup coil.

Integrated-type SQUID magnetometer having a magnetic shield, and a

A SQUID for detecting a weak magnetic field is constructed of a sensor coil which detects a signal magnetic flux, and a superconducting loop which is magnetically coupled with the sensor coil to generate a periodic voltage corresponding to an interlinking magnetic flux from the sensor coil. The periodic voltage from the SQUID is amplified, and is taken out. The periodic voltage taken out is synchronously detected by a phase-sensitive detecting amplifier. The synchronously-detected signal is converted into a light signal, which is fed back to the SQUID. The light signal fed back is converted into an electric signal by a superconducting phototransistor which is arranged in a cryogenic atmosphere. A magnetic flux corresponding to the electric signal from the superconducting phototransistor is fed back to the superconducting loop by a feedback coil.

Magnetometer using a Josephson device and superconducting phototransistor

In a signal detecting circuit of, for example, an NMR apparatus, a signal transmission path transmits an AC magnetic flux signal to be superposed on a DC magnetic field whose strength does not change with time during a period of signal detection. The signal transmission path comprises a superconducting closed loop including a receiving coil receiving the AC magnetic flux signal, an input coil applying the received AC magnetic flux signal as an input to a flux meter, and a variable resistor replacing part of the superconducting closed loop and having its resistance value changed in relation to a change in the strength of the DC magnetic field.

Circuit for detecting AC magnetic field due to magnetic resonance with a

A superconducting current detecting circuit which comprises a reference current generation circuit for generating a reference current and a DC flux parametron circuit for comparing an input current to be detected with the reference current to thereby produce pulses in synchronism with an input excitation signal, the number of the pulses being varied in accordance with a difference between the input current and the reference current, the pulses having positive or negative values depending on the polarity of the difference, the reference current generation circuit having means for increasing or decreasing the reference current by a quantity corresponding to the number of the pulses in response to the polarity of the pulses so that reference current generation circuit produces the reference current which agrees with the input current.

Superconducting current detecting circuit employing DC flux parametron

Disclosed in a nuclear magnetic resonance (NMR) based inspection apparatus using an SQUID flux meter for detecting a small NMR signal, in which a receiving coil for receiving the NMR signal from an object is connected to a mixer, which mixes a reference high-frequency signal with the NMR signal so that the NMR signal is reduced to a low-frequency signal having a differential component of frequencies of both signals, and the low-frequency signal is applied to the input coil of the SQUID flux meter so that it is converted into a voltage signal. The mixer circuit includes Schottky diodes operative at a liquid helium temperature or Josephson junctions, and the portions of apparatus from the reception coil up to the SQUID flux meter are operated in a superconductive state at a liquid helium temperature.

Growing community of inventors

Hachioji, Japan

Hideaki Nakane