Cross-whisker junction as a tunable SIS tunneling junction - An application of the d-wave symmetry of the high-Tc superconductor

Abstract

The cross-whisker junction can be fabricated with considerable ease. It is made by simply placing two whiskers crosswise on an MgO substrate and heating for a short time. We have found that the Josephson characteristics exhibit a novel dependence on the crossing angle between the two whiskers. This phenomenon turns out to reflect the d-wave nature of the high-Tc superconductors. The Josephson parameters can be controlled artificially by varying the crossing angle. We have successfully observed the Shapiro step, Fraunhofer pattern and SQUID response taking advantage of the tunability of the Josephson parameters. The developments of new devices utilizing the d-wave symmetry of the high-Tc superconductors are anticipated.