T. Hato

T. Hato
International Superconductivity Technology Center

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70
Publications
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476
Citations
Introduction

Publications

Publications (70)
Article
Full-text available
We developed a hybrid cooling system consisting of a liquid-nitrogen Dewar and a cryocooler with the aim of cooling HTS-SQUIDs fast at operation sites, extending cooling period time, and avoiding noise increase caused by the cryocooler. Liquid nitrogen is evaporated mainly by thermal inflow into the Dewar. Thus, we tried reducing the thermal inflow...
Article
To perform an early stage detection of the deteriora-tion of steel parts used in infrastructures, a nondestructive testing method is required, which is capable of evaluating hidden parts, such as a steel deck covered with an asphalt pavement. To achieve this, a magnetic field detector should be sufficiently large to detect magnetic fields over a wi...
Article
We have developed a three-channel HTS-SQUID eddy current testing (ECT) system for detection of a fatigue crack which occurs in a steel deck plate used in expressway bridges. To avoid physical interference between adjacent channels, a dipole coil with compact design is employed. A field test using the three channel ECT system was performed on an exp...
Article
Full-text available
We propose an HTS-SQUID vector magnetometer with a new configuration reducing the crosstalk between a pickup coil of one SQUID and feedback coils of other SQUIDs. The new configuration is designed to mount three SQUIDs at symmetric positions where the crosstalk should be ideally zero while keeping minimal height of a probe head. In an actual HTS-SQ...
Article
We examined a portable cryostat utilizing liquid nitrogen with temperature control function for operation of high-temperature superconducting quantum interference devices (HTS-SQUIDs) to have a higher slew rate. To operate a non-destructive evaluation system with HTS-SQUID in city areas with serious environmental electromagnetic noise, we often nee...
Article
We examined the design method of a glass Dewar for liquid nitrogen as a cooling apparatus of an HTS-SQUID system for field use. Cooling technique without stressing operators is very important. Though cooling technique using liquid nitrogen is suitable to cool HTS-SQUIDs fast at an operation site and operate them without additional noise, the operat...
Article
We have been developing an HTS-SQUID eddy current testing (ECT) system using an HTS-SQUID module and external pickup coil made of Bi-2223 tape to investigate the feasibility of non-destructive evaluation of a steel plate paved with asphalt. In this work, a new excitation coil intended as a current dipole source is designed and evaluated. The curren...
Article
We fabricated HTS-SQUID magnetometers with ramp-edge-type Josephson junctions and measured their noise properties using dc/ac biasing mode. Some exhibited lowered low-frequency noise by ac biasing and others did not. We compared various parameters to find correlative ones with effectiveness of ac biasing. We found that the junction width and the cr...
Article
Our research group reported successful observation of “co-faulting” Earth’s magnetic field changes because of piezomagnetic effects caused by earthquake tremors during the 2008 Iwate-Miyagi Nairiku earthquake of M7.2 using a geomagnetic observation system with flux-gate magnetometers. This is an important finding: electromagnetic fields propagate f...
Article
Direct detection of magnetic fields generated by the ion currents in electrolytic cells was performed and the ion currents were mapped during a cyclic voltammetry experiment. A high-TC superconducting quantum interference device (SQUID) gradiometer with ramp-edge Josephson junctions was used as the detector and thus the first derivative of the magn...
Article
For the transient electromagnetic (TEM) method using a high-temperature superconducting interference device (HTS-SQUID), we have developed a magnetometer system with a wide dynamic range, a high slew rate, and superior transportability. To achieve high tolerance to a higher excitation magnetic field, we utilized a SQUID magnetometer containing ramp...
Article
The key point of this presentation is that we successfully develop the high-temperature-superconductor based superconducting-quantum-interference-device (HTS-SQUID) magnetometer system for super-sensitive observation of geomagnetic field changes. Electromagnetic changes associated with earthquakes have been investigated previously. Our research gr...
Article
We have investigated the fabrication of a high-temperature superconducting (HTS) gradiometer with long baseline for geophysical applications. The proof-of-concept gradiometer using a 1-turn pickup coil made of a GdBa2Cu3Oy coated conductor (GCC) and 5.5-turn input coil integrated on a SQUID was fabricated in our previous work. In this study, we hav...
Article
We have fabricated a large high-Tc superconducting (HTS) SQUID gradiometer with a baseline length of 130 mm for geophysical application. It consists of an HTS-SQUID gradiometer chip with an integrated input coil and a large pickup coil made of an HTS coated conductor (CC). In this work, fabrication of the chip containing ramp-edge Josephson junctio...
Article
Full-text available
We have developed a new eddy-current non-destructive evaluation (NDE) system using an HTS SQUID gradiometer with the aim of applying it to practical materials with magnetization. The new NDE system employs a LN2-cooled external Cu pickup coil and an HTS SQUID chip placed in a magnetic shield made of HTS material. The HTS SQUID chip consists of an H...
Article
We have developed a new fabrication method for a high-Tc superconducting quantum interference device (SQUID) with an integrated multiturn input coil to improve the fabrication yield. The method consists of a new multi-SQUID layout and an additional patterning process. In this layout, each input coil is shunted by a shunt inductor to avoid an increa...
Article
Recent developments of electronic devices containing Josephson junctions (JJ) with high-Tc superconductors (HTS) are reported. In particular, the fabrication process and the properties of superconducting quantum interference devices (SQUIDs) with a multilayer structure and ramp-edge-type JJs are described. The JJs were fabricated by re-crystallizat...
Article
We developed a non-destructive evaluation (NDE) technique combining the high-speed scanning laser observation system and the SQUID gradiometer array system for multi-filamentary coated conductors (CCs). The high-speed scanning laser observation system can detect anomalies in height of the surface and reflectivity, and marks the information of defec...
Article
We have studied the fabrication process for high-Tc superconducting quantum interference devices (HTS-SQUIDs) containing ramp-edge-type Josephson junctions and multilayer superconducting wiring. Integrated HTS-SQUID magnetometers with a 20-turn input coil were fabricated. SmBCO and La-doped ErBCO were used for base- and counter-electrodes having Tc...
Article
With the aim of clarifying the origin of local defects in coated conductors (CCs) and feeding back to the fabrication process, we have examined the distribution of defects in each layer of a CC which has Ag/GdBCO/CeO<sub>2</sub>/LaMnO<sub>3</sub>(LMO)/IBAD -MgO/Gd<sub>2</sub>Zr<sub>2</sub>O<sub>7</sub>(GZO)/Hastelloy structure by means of a high-sp...
Article
We examined the ability to detect deep-lying defects in multilayer stacks of aluminum plates using an eddy-current testing technique with HTS planar-type SQUID gradiometers. In addition to a previous gradiometer with a baseline of 1 mm, a new gradiometer with a baseline of 8.5 mm and a larger effective area fabricated by HTS multilayer and ramp-edg...
Article
We have studied the fabrication process of HTS-SQUIDs with ramp-edge Josephson junctions (JJs). SmBa<sub>2</sub>Cu<sub>3</sub>O<sub>y</sub> (SmBCO) and Er<sub>0.95</sub>La<sub>0.1</sub>Ba<sub>1.95</sub>Cu<sub>3</sub>O<sub>y</sub> (L1ErBCO) having T <sub>c</sub>'s around 90 K were used for base- and counter-electrodes, respectively. SrSnO<sub>3</sub...
Article
We have fabricated a two-axis high-T<sub>c</sub> planar gradiometer. Two gradiometers with planar gradiometric pickup coils lie diagonally on a square substrate. Therefore, they can measure field gradients, dBz/dx and dBz/dy at the same site. The two-axis gradiometer was fabricated on a 15 × 15 mm MgO (100) substrate using an HTS multilayer process...
Article
We have fabricated a large high-temperature superconducting gradiometer for geophysical application such as a Transient Electro-Magnetic (TEM) method. The seamless gradiometric pickup coil was made of a commercially available GdBCO coated conductor formed on a Hastelloy tape. Two pickup loops with a diameter of 100 mm and an integrated input coil o...
Article
We have studied the fabrication process for high-Tc superconducting quantum interference devices (HTS-SQUIDs) containing ramp-edge-type Josephson junctions and multilayer superconducting wiring. 5-Channel gradiometer arrays for non-destructive evaluation of striated coated conductors were fabricated. Our previous process contained some problems whi...
Article
We examined the ability of detecting defects in multilayer aluminum plates by using an HTS SQUID gradiometer in an unshielded environment. The planar HTS SQUID gradiometer with 1mm×1mm pickup loops and 1mm baseline was fabricated by using HTS multilayer and ramp-edge junction technologies, and cooled by thermal conduction from a LN2 cryostat. We tr...
Article
We developed a non-destructive evaluation (NDE) system using an HTS SQUID array in order to examine rare-earth (RE)-123 HTS coated conductors striated into multi-filamentary lines. The 5-channel HTS SQUID gradiometer array was composed of ramp-edge junctions with LaErBaCuO and SmBaCuO electrode layers, and fabricated by using an HTS multi layer fab...
Article
We have fabricated high-temperature superconductor (HTS) dc superconducting quantum interference devices (SQUIDs) with a multilayer structure and ramp-edge Josephson junctions. For stable operation at 77 K, SmBa<sub>2</sub>Cu<sub>3</sub>O<sub>y</sub> (SmBCO) and La<sub>0.1</sub>-Er<sub>0.95</sub>Ba<sub>1.95</sub>Cu<sub>3</sub>O<sub>y</sub> (La-ErBC...
Article
We developed a non-destructive testing (NDT) system utilizing multi-channel high-temperature superconductor (HTS) SQUID gradiometers in order to examine rare earth (RE)-123 coated conductors striated into multi-filamentary lines. The 5-channel HTS SQUID gradiometer array was composed of ramp-edge junctions with LaErBaCuO and SmBaCuO electrode layer...
Article
We proposed a novel multilayer structure having a new combination of oxides for integrated high-Tc SQUID with ramp-edge Josephson junctions. La0.1Er0.95Ba1.95Cu3Oy (L1ErBCO) and SmBa2Cu3Oy (SmBCO) were used as counter- and base-electrodes, respectively. An SrSnO3 (SSO) layer was deposited as an insulating layer. Prior to deposition of SmBCO, Pr1.4B...
Article
We have developed the fabrication process, the circuit design technology, and the cryopackaging technology for high-Tc single flux quantum (SFQ) devices with the aim of application to an analog-to-digital (A/D) converter circuit for future wireless communication and a sampler system for high-speed measurements. Reproducibility of fabricating ramped...
Article
We improved the fabrication technology of high-temperature superconducting (HTS) single-flux-quantum (SFQ) circuits by suppression of oxygen loss. Among a lot of difficulties in the HTS circuit fabrication process, loss of oxygen is one of the most significant problems. To understand the oxygen going in and out at each step of the fabrication proce...
Article
We have succeeded in observing a pico-second current pulse accompanying a single flux quantum (SFQ) using a high-Tc superconducting (HTS) sampler. The sampler circuit used in this study, an on-chip sampler, has two pulsers connected to each other at the comparator in one chip. The waveform of an SFQ current pulse from one pulser is measured by usin...
Article
This paper describes a compact cooling system using a single-stage stirling-type cryocooler for a practical HTS sampler. The system was designed to cool down an HTS sampler module below 50K, enabling a bandwidth of the chip more than 100GHz. The system measures 150mm in width, 140mm in height and 310mm in depth, and weighs 5kg. Semi-rigid coaxial c...
Article
We are developing waveform measurement systems using a high- superconducting (HTS) sampler. As one of the methods for introducing high-frequency signals into the sampler chip, we are testing optical input systems. A uni-traveling-carrier photodiode (UTC-PD), which has potential bandwidth of over 300 GHz, is used in the systems for converting optica...
Article
This paper reviews our progress on the high- T c superconducting (HTS) sampler development, covering from the circuit design to the latest experimental data in the sinusoidal and pulse waveform measurements. A computer simulation has revealed that our sampler circuit with an improved design enables waveform measurement with the bandwidth over 100 G...
Article
We have studied the effect of thermal noise and trigger jitter on the bandwidth of a high-T<sub>c</sub> superconducting sampler by computer simulation and analytical calculation. Simulation results showed that the minimum I<sub>c</sub>R<sub>n</sub> product of the junctions required to obtain 100-GHz bandwidth is raised from 0.63 to 0.75 mV under th...
Article
Photosensitive polyimide was selected as a protection layer for the YBa2Cu3O7−x circuits and stability of ramp-edge-junction characteristics against atmospheric moisture was investigated. Both coating and patterning of the protection layer could simultaneously be formed on the ramp-edge-junctions by using the polyimide film. Characteristic change o...
Article
We improved the fabrication process of high-temperature superconducting (HTS) sampler circuits with multilayer structures by utilizing a test elements group (TEG). Among a lot of difficulties in the HTS circuit fabrication process, loss of oxygen is one of the most significant problems. Since the film transition temperature (Tc) has a strong relati...
Article
We have investigated the flux state in high- and low-Tc SFQ circuits having superconducting ground planes with moats by a scanning SQUID microscope (SSM) system. Observation of YBa2Cu3Oy (YBCO) sampler circuits having superconducting ground planes with 5 µm-wide moats confirmed that magnetic flux was excluded from the moat-surrounded area including...
Article
We propose a new ion etching procedure to level the surfaces of lower layers in multilayer structures for HTS SFQ circuits. In order to make a flat lower layer, we have utilized a variation in the etching rate with the ion incident angle in ion etching process. The etching process under the acceleration voltage of 280 V and the ion incident angle a...
Article
This paper describes an overview of our plan and recent progress on the HTS sampler development with the aim of demonstrating its potential performance of a bandwidth over 100 GHz using a compact cryocooler. Several changes from the NEC’s former work have been made in the device fabrication process, the circuit design and the system design. We empl...
Article
We succeeded in observing high-frequency current waveforms up to 45GHz using a high-temperature superconducting (HTS) sampler. In this experiment, we used a sampler circuit with a superconducting pickup coil, which magnetically detects current signals flowing through a micro-strip line on a printed board placed outside the cryochamber. This type of...
Article
We constructed a laser-plume monitoring system to stabilize fabrication process of high-temperature superconducting (HTS) circuits with films and junctions prepared by a laser ablation method. The system utilizing a CCD camera with wide band sensitivity accumulates intensity of ultraviolet ray for many plumes as an averaged matrix data of 256×256....
Article
We have investigated the flux state in YBa2Cu3Oy (YBCO) sampler circuits having superconducting ground planes with 5 or 7-μm-wide moats by a scanning SQUID microscope (SSM) system. It was found that magnetic flux was trapped into continuous moats with the length larger than 20 μm, and magnetic flux was excluded from the moat-surrounded area which i...
Article
We investigated high-T<sub>c</sub> superconducting sampler circuits by computer simulation and proved that our latest version of sampler circuit can operate with bandwidth over 100 GHz. In our conventional sampler circuit, we found several problems in its circuit design. An improved sampler circuit, which has additional reset junctions in the dc/SF...
Article
We propose an output interface with a latching driver for single-flux-quantum (SFQ) circuits operating at 4.2 K. An optimum critical current density J<sub>c</sub> of the latching driver was discussed, and a multichip module (MCM) structure with SFQ circuits and latching drivers was proposed for 40-Gb/s operation. To optimize J<sub>c</sub> of the la...
Article
We report on a latching-type driver operated at 30 K for the output interface of single-flux-quantum (SFQ) circuits. Ramp-edge-type high-temperature superconductor (HTS) junctions showed only small inherent hysteresis in current–voltage characteristics at a temperature of 30 K. To have hysteresis large enough for latching operation, we chose La-dop...
Article
Latching-type driver circuits integrated with high-temperature superconductivity (HTS) junctions and two types of resistor were fabricated. These circuits could successfully perform latching operation by means of a single-flux-quantum (SFQ) signal input. Ramp-edge-type HTS junctions were fabricated by interface engineering and showed a hysteretic c...
Article
A ramp-edge junction was fabricated with 200-nm-thick YBa2Cu3O7−x (YBCO) electrodes and an intermediate insulating layer of 300-nm-thick LaSrAlTaO (LSAT). Extraneous electrode areas are placed on top of their ramps as a result of the fabrication process. The junction exhibited an RSJ-like I–V curve with a swelling or steps depending on the shape of...
Article
We developed a latching-type driver using capacitively shunted high-temperature superconductivity (HTS) junctions for Single-Flux-Quantum (SFQ)-semiconductor output interfaces and fabricated it using ramp-edge-type HTS junctions. Assuming a junction IcRn product of 2 mV, a circuit simulation shows that the driver can produce an output of about 8 mV...
Article
We fabricated a ramp-edge Josephson junction with a 17-nm-thick indium-tin-oxide (ITO) (1 wt%) barrier. ITO is considered to be a useful barrier material for Josephson junctions because it has a low permittivity of 20, a mobility of 100 cm2/V·s, a carrier density of 1.1×1020 cm-3, and (100) orientation on YBa2Cu3O7-x (YBCO) (001). We examined 8 jun...
Article
The dielectric-base transistor (DBT) is expected to be coupled with various functional oxides such as high-temperature superconductors and ferroelectrics. We experimented with lowering the conduction band of the channel to reduce the operating voltage. LaTiO3 deposited on SrTiO3 supplies carriers in the SrTiO3 substrate by displacing Sr2+ and La3+....
Article
We studied In2O3 for use as an intermediate layer between the YBCO emitter electrode and the SrTiO3 base region of dielectric-base transistors (DBT). We fabricated and tested a YBCO(001)/In2O3(100)/SrTiO3(110) hetero-structure by using a laser-ablation deposition technique with high-density targets. Our YBCO/In2O3/n-SrTiO3 diode structure showed a...
Article
As a first step toward fabricating transistors to control supercurrent, we fabricated two- and three-terminal devices that have coplanar Nb electrodes coupled with a SrTiO<sub>3</sub> substrate. In the two-terminal devices, the Nb electrodes were coupled with an Nb-doped SrTiO<sub>3</sub> substrate with a carrier concentration of 2×10<sup>19</sup>...
Article
Expression of CD4 or CD8 on the cell surface is an important guide for discriminating the immunologic functions of T-cells. However, a minor T-cell subset lacking both CD4 and CD8 molecules but bearing the usual form of T-cell receptor (TCR)-alpha beta (CD4-CD8-TCR-alpha beta+ T-cells) has recently been found not only in mice but also in humans, an...
Article
We measured the current-voltage characteristics of YBa<sub>2</sub>Cu<sub>3</sub>O<sub>7-x</sub>/oxide/n-SrTiO<sub>3</sub> diodes using NdGaO<sub>3</sub>, LaAlO<sub>3</sub>, CeO<sub>2</sub>, and MgO as the oxide. MgO films had the highest current density. We then fabricated dielectric-base transistors with a YBa<sub>2</sub>Cu<sub>3 </sub>O<sub>7-x</...
Article
We present an immunocompetent patient with transfusion-associated graft-versus-host disease (GVHD), in which chimaerism of peripheral blood lymphocytes was demonstrated by analysis of a highly polymorphic genome. The patient was treated successfully with anti-CD3 monoclonal antibody, OKT3 and cyclosporin A. Although it is undoubtedly important to p...
Article
In most patients with large granular lymphocyte (LGL) leukemia, the disease appears to progress slowly if at all, and no therapy is generally required. We present a patient with CD3+ CD8+ CD16+ LGL leukemia, who showed a benign clinical course for more than 7 months without therapy, but subsequently developed aggressive disease. A feature of consid...
Article
The earliest T-lineage precursor cells with a CD3-CD4+CD8- phenotype and germline-state T-cell receptor (TCR) genes have recently been identified in the murine thymus. We report a case of malignant lymphoma that was considered to originate from the human counterpart of this newly defined murine T-cell population. The surface phenotype of the lympho...
Article
Immunological analysis of 2 cases of granular lymphocyte proliferative disorder with clonal expansion of CD3+4-8+ T cells bearing either T cell receptor alpha/beta (patient 1) or T cell receptor gamma/delta (patient 2) is reported. Significant cytotoxic activity against K562 was observed in peripheral blood mononuclear cells (PBMC) isolated from pa...
Article
Inversion of chromosome 16 was found in a 73-year-old female with acute myeloblastic leukemia (FAB:M2). Complete remission was achieved by combined chemotherapy (DNR, Ara-C, 6-MP, Prednisolone), but she relapsed 6 months later without CNS involvement and died of respiratory failure presumably due to cerebrovascular accident during remission reinduc...
Article
We found that a monoclonal antibody to the glycoprotein (GP) IIb-IIIa complex, PMA4, induces fibrinogen binding to platelets, and we examined the mechanism involved. Affinity chromatography and crossed immunoelectrophoresis showed that PMA4 recognized an epitope on the GPIIb-IIIa complex-specific domain. The binding of 125I-fibrinogen to platelets...
Article
The mechanism of eosinophilia in a patient with adult T cell leukemia (ATL) was investigated. A 61-year-old woman with ATL presented marked eosinophilia. No parasite infections or allergic diseases were found in this patient. The number of eosinophils fluctuated in parallel with that of ATL cells during her clinical course. The patient's serum and...
Article
Superconductor-semiconductor-superconductor (S-N-S) weak-link junctions with a normal layer of Si or InSb thin films were prepared by using focused ion beam (FIB) methods. The electrical properties were measured. Whereas InSb thin films on single crystals did not have an intrinsic mobility, S-N-S junctions with InSb show the characteristics of a Jo...
Article
Superconducting thin films of Y-Ba-Cu-O and Bi-Ca-Sr-Cu-O were prepared by the flash evaporation technique. The flash evaporation method evaporates multi-elements instantly with different evaporation temperatures. These films had critical temperatures T <sub>c </sub> (zero resistance) of 78 K (unannealed Y-Ba-Cu-O) and 73 K (annealed Bi-Ca-Sr-Cu-O)...

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