Satoshi KASHIWAYA

Senior Research Scientist, Electronics and Photonics Research Institute, Advance Industrial Science and Technology

Field of Specialty：

Low temperature physics, tunneling effect

Topics of Research：

(A01) Novel Edge Phenomena in Superconductors with Broken Time-Reversal Symmetry

Specific Topics：

Tunneling effects in superconductors with broken time reversal symmetry

■ Laboratory Website

RESEARCH

Most of novel superconductors discovered in recent years have anisotropic electronic states and internal degrees of freedom in their superconducting order parameters. At a surface of such novel superconductors, the quasiparticle bound states so called Andreev bound states are formed as a result of broken translational symmetry. The formation of the surface or edge states seriously modifies low energy transport properties of tunneling junctions such as normal/insulator/superconductor (NIS) and superconductor/insulator/superconductor (SIS). The identification of superconducting pairing symmetry is basically possible by analyzing tunneling spectra of superconductors because the tunneling current tells us the quasiparticle density of states of the Andreev bond states well reflecting the pairing symmetries. Actually we detected the zero bias conductance peaks (ZBCP) at the surface on (110) oriented YBa₂Cu₃O₇ using low-temperature Scanning Tunneling Spectroscope (STS), which is consistent with theoretical prediction assuming d_x2-_y2 symmetry.

In this project, we are planning to clarify the transport properties in tunneling junctions consisting Sr₂RuO₄. Various experimental results have suggested the spin-triplet chiral p-wave symmetry in Sr₂RuO₄. Since the chiral p-wave symmetry breaks time reversal symmetry, novel types of bound state, called chiral Majorana edge state, is strongly expected at an edge of Sr₂RuO₄. We have already fabricated tunneling junctions of Sr₂RuO₄ using the focused ion beam (FIB) and the in-situ deposition processes. At present, we are planning to detect the chiral edge states, a half flux quantum, Majorana Fermion excitation using the tunneling spectroscopy. We expect that our experimental results would contribute to establishing the chiral p-wave symmetry in Sr₂RuO₄.

PROFESSIONAL EXPERIENCE

1988-1995

Research associate, Electrotechnical Laboratory, Agency of Industrial Science and Technology

1995-2001

Chief researcher, Electrotechnical Laboratory, Agency of Industrial Science and Technology

2001 -Present

Leader, Low-temperature physics Group, Nanoelectronics Research Institute, Advance Industrial Science and Technology

HONORS AND AWARDS

2000

Japan IBM Science Award

2005

Superconductivity Science and Technology Award

SELECTION OF PUBLICATIONS