Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

Japanese Journal of Applied Physics

Submillimeter-Wave Response of Nb-YBaCuO Point-Contact Josephson Junctions Using YBaCuO Thin Films Prepared by CVD

Syozo Imai, Nobuhiro Sugawara, Kazushige Sumiya, Kimihiko Ito, Nobuo Mikoshiba, Hisanori Yamane, T. Hirai, Hideyuki Kurosawa, Tsutomu Yamashita

Published Oct 1, 1990• 2 citations
Publisher

Abstract

The Shapiro steps in the submillimeter wave (SMMW) region were measured in point-contact Josephson junctions made of a Nb strip with a sharpened edge and a YBaCuO thin film. The thin film was prepared by the chemical vapor deposition (CVD) method. The dependence of the Shapiro step width on the SMMW power was measured for the wavelength of 570.6 µm (525.4 GHz). The dependence was similar to that found in microbridges made of low T c superconductors. The first-order Shapiro step was observed for the wavelength of 232.9 µm (1.287 THz).

DOI
10.1143/jjap.29.l1778

Related papers

Submillimeter-Wave Response of Nb-YBaCuO Point-Contact Josephson Junctions

Syozo Imai, Tadayuki Tozawa, Gin-ichiro Oya +3 more

Shapiro steps in the submillimeter-wave (SMMW) range were observed in junctions made of a high-T c superconductor, YBa2Cu3O x (YBaCuO), and niobium. Junctions were made by pressing a Nb needle on a sintered YBaCuO disk. Shapiro steps up to the fifth order were observed for SMMWs of wavelength 871.6 µm (frequency 344.0 GHz). The dependence of the Shapiro step width on the SMMW power is in accordance with the Bessel function dependence. For SMMWs of wavelength 570.6 µm (525.4 GHz), Shapiro steps up to the second order were observed.

Japanese Journal of Applied Physics•Apr 1, 1988•6 citations

Nonlinear response of tunnel-type Josephson junctions at submillimeter-wave frequencies

S. Morita, S. Takaki, S. Imai +2 more

We have fabricated tunnel-type Josephson junctions with very small junction area by pressing the tip of a sharpened Nb wire onto a thinly oxidized Sn film, and studied their submillimeter-wave responses. It turns out that the junctions have a very high cutoff frequency, and are suitable for the investigation of the response to the submillimeter waves with the frequency higher than 1 THz. From the frequency and laser-power dependence of the Shapiro step, it is found that the tunnel-type junction shows much larger higher-order steps, and accordingly has much stronger nonlinearity than the bridge-type junction in the submillimeter-wave region. The large enhancement of the steps due to the Riedel singularity is also observed in the tunnel-type junction. In addition to the Shapiro steps, photon-assisted tunneling steps are observed clearly, reflecting the large and sharp gap structure in the dc IV curves of the tunnel-type junctions.

IEEE Transactions on Magnetics•May 1, 1983•6 citations

Frequency Dependence of the Submillimeter-Wave Response in the Tunnel-Type and Bridge-Type Josephson Junctions

Seizo Morita, Satoru Takaki, Syozo Imai +2 more

We have fabricated ultrasmall tunnel-type Josephson junctions with Nb–SnO x –Sn film point-contacts. Using these junctions, we have measured for the first time the Shapiro steps in the submillimeter-wave region and have compared the strength of steps of this junction with that of the bridge-type Nb–Sn ingot point-contacts. We found that the tunnel-type junction shows a sharper Riedel peak than the bridge-type junction.

Japanese Journal of Applied Physics•Jun 1, 1982•6 citations

High T/sub c/ superconducting step-edge junctions and their properties in millimeter-wave band

Yijun Feng, L. Kang, X. B. Wang +8 more

Superconducting step-edge junctions were fabricated on step-edges in (100) LaAlO/sub 3/ substrates by sputter-deposited epitaxial YBaCuO and TlBaCaCuO thin films. The substrate steps were patterned by ion beam etching using metal film as a mask. The transport properties of the junctions were characterized by four-probe electrical measurements. The critical current-normal resistance product (I/sub c/R/sub N/) was larger than 0.2 mV (77 K) for most of the junctions. Clear Shapiro steps were observed in the current-voltage characteristics of the junctions with 36 GHz or 95 GHz millimeter-wave irradiation. The high frequency properties of these high T/sub c/ Josephson junctions showed that they were quite suitable for the Josephson harmonic mixer used in the digital phase locked millimeter and sub-millimeter wave sources.>

IEEE Transactions on Applied Superconductivity•Jun 1, 1995•1 citation

Microwave Heterodyne Mixing by Step-Edge Microbridge Josephson Junctions Using YBaCuO Thin Films

Yoshito Fukumoto, Hiroshi Kajikawa, Rikuo Ogawa +1 more

Current-voltage characteristics and microwave mixing properties of step-edge microbridge Josephson junctions (SEJJs) made of YBaCuO thin films were systematically investigated. The step-edge was formed on the surface of a MgO(100) substrate employing the common photolithograph and wet-etching techniques. YBaCuO thin film was deposited by the off-axis sputtering method, and the microbridge junctions were fabricated so as to cross the step-edge. The SEJJs showed typical DC and AC characteristics which were explained by the resistively shunted junction (RSJ) model. Mixing experiments were carried out in the K-band microwave region. An intermediate frequency (IF) output with the frequency range of 20 MHz∼2.0 GHz was successfully obtained.

Japanese Journal of Applied Physics•Dec 1, 1991•17 citations

Microwave Heterodyne Mixing by Step-Edge Microbridge Josephson Junctions Using YBaCuO Thin Films

Yoshito Fukumoto, Hiroshi Kajikawa, Rikuo Ogawa +1 more

Current-voltage characteristics and microwave mixing properties of step-edge microbridge Josephson junctions (SEJJs) made of YBaCuO thin films were systematically investigated. The step-edge was formed on the surface of a MgO(100) substrate employing the common photolithograph and wet-etching techniques. YBaCuO thin film was deposited by the off-axis sputtering method, and the microbridge junctions were fabricated so as to cross the step-edge. The SEJJs showed typical DC and AC characteristics which were explained by the resistively shunted junction (RSJ) model. Mixing experiments were carried out in the K-band microwave region. An intermediate frequency (IF) output with the frequency range of 20 MHz~2.0 GHz was successfully obtained.

International Conference on Solid State Devices and Materials (SSDM)•Aug 28, 1991•0 citations
The Shapiro steps in the submillimeter wave (SMMW) region were measured in point-contact Josephson junctions made of a Nb strip with a sharpened edge and a YBaCuO thin film. The thin film was prepared by the chemical vapor deposition (CVD) method. The dependence of the Shapiro step width on the SMMW power was measured for the wavelength of 570.6 µm (525.4 GHz). The dependence was similar to that found in microbridges made of low T c superconductors. The first-order Shapiro step was observed for the wavelength of 232.9 µm (1.287 THz).
Shapiro steps in the submillimeter-wave (SMMW) range were observed in junctions made of a high-T c superconductor, YBa2Cu3O x (YBaCuO), and niobium. Junctions were made by pressing a Nb needle on a sintered YBaCuO disk. Shapiro steps up to the fifth order were observed for SMMWs of wavelength 871.6 µm (frequency 344.0 GHz). The dependence of the Shapiro step width on the SMMW power is in accordance with the Bessel function dependence. For SMMWs of wavelength 570.6 µm (525.4 GHz), Shapiro steps up to the second order were observed.
We have fabricated tunnel-type Josephson junctions with very small junction area by pressing the tip of a sharpened Nb wire onto a thinly oxidized Sn film, and studied their submillimeter-wave responses. It turns out that the junctions have a very high cutoff frequency, and are suitable for the investigation of the response to the submillimeter waves with the frequency higher than 1 THz. From the frequency and laser-power dependence of the Shapiro step, it is found that the tunnel-type junction shows much larger higher-order steps, and accordingly has much stronger nonlinearity than the bridge-type junction in the submillimeter-wave region. The large enhancement of the steps due to the Riedel singularity is also observed in the tunnel-type junction. In addition to the Shapiro steps, photon-assisted tunneling steps are observed clearly, reflecting the large and sharp gap structure in the dc IV curves of the tunnel-type junctions.
Superconducting step-edge junctions were fabricated on step-edges in (100) LaAlO/sub 3/ substrates by sputter-deposited epitaxial YBaCuO and TlBaCaCuO thin films. The substrate steps were patterned by ion beam etching using metal film as a mask. The transport properties of the junctions were characterized by four-probe electrical measurements. The critical current-normal resistance product (I/sub c/R/sub N/) was larger than 0.2 mV (77 K) for most of the junctions. Clear Shapiro steps were observed in the current-voltage characteristics of the junctions with 36 GHz or 95 GHz millimeter-wave irradiation. The high frequency properties of these high T/sub c/ Josephson junctions showed that they were quite suitable for the Josephson harmonic mixer used in the digital phase locked millimeter and sub-millimeter wave sources.>
Current-voltage characteristics and microwave mixing properties of step-edge microbridge Josephson junctions (SEJJs) made of YBaCuO thin films were systematically investigated. The step-edge was formed on the surface of a MgO(100) substrate employing the common photolithograph and wet-etching techniques. YBaCuO thin film was deposited by the off-axis sputtering method, and the microbridge junctions were fabricated so as to cross the step-edge. The SEJJs showed typical DC and AC characteristics which were explained by the resistively shunted junction (RSJ) model. Mixing experiments were carried out in the K-band microwave region. An intermediate frequency (IF) output with the frequency range of 20 MHz∼2.0 GHz was successfully obtained.
Current-voltage characteristics and microwave mixing properties of step-edge microbridge Josephson junctions (SEJJs) made of YBaCuO thin films were systematically investigated. The step-edge was formed on the surface of a MgO(100) substrate employing the common photolithograph and wet-etching techniques. YBaCuO thin film was deposited by the off-axis sputtering method, and the microbridge junctions were fabricated so as to cross the step-edge. The SEJJs showed typical DC and AC characteristics which were explained by the resistively shunted junction (RSJ) model. Mixing experiments were carried out in the K-band microwave region. An intermediate frequency (IF) output with the frequency range of 20 MHz~2.0 GHz was successfully obtained.