RESEARCH

We are interested in proximity effect of superconductor/diffusive metal junctions and the relation between topological number and a odd in time Cooper pairing amplitude. For a conventional s-wave superconductor/diffusive metal junction, the local density of states in diffusive metal reflects the shape of the gap function of the superconductor since s-wave Cooper pairing is robust against impurity scattering. However for unconventional p-wave superconductor/diffusive metal junction, zero energy peak appears due to the presence of a odd in frequency s-wave Cooper pair amplitude. Recently, we found such a anomalous proximity effect can be occur for a d-wave superconductor with strong spin-orbit interaction since the odd in frequency s-wave Cooper pair amplitude is generated. We also found that there is a relation between a one-dimensional winding number and odd in frequency s-wave Cooper pair amplitude. The winding number can be defined if the system has chiral symmetry: a Hamiltonian anticommutes with a chiral operator. In chiral symmetric systems, there are two kinds of odd in frequency Cooper pair amplitude, one is a singular function of frequency: A/z (A is the winding number and it is integer and z is a frequency) and the other is a regular function of frequency: Bz (B is a coefficient). Near the topological transition point, where A changes, we found that B diverges like a susceptibility diverges near phase transition points.

EDUCATION

2011

B.Sc. in Tohoku University

2013

M.S. in Tohoku University

2016

Ph.D. in Tohoku University

PROFESSIONAL EXPERIENCE

2013-2016

Researcher, Japan Society for the Promotion of Science

2016-Present

PD Researcher, Department of Applied Physics, Nagoya University

SELECTION OF PUBLICATIONS

"Surface Andreev Bound States and Odd-Frequency Pairing in Topological Superconductor Junctions"
Yukio Tanaka and Shun Tamura
Journal of Low Temperature Physics 191, 61-83 (Apr. 2018)
https://doi.org/10.1007/s10909-018-1849-8

"Theory of surface Andreev bound states and tunneling spectroscopy in three-dimensional chiral superconductors"
Shun Tamura, Shingo Kobayashi, Lu Bo, and Yukio Tanaka
Physical Review B 95, 104511-1-22 (Mar. 2017)
DOI: 10.1103/PhysRevB.95.104511

"Current fluctuations in unconventional superconductor junctions with impurity scattering"
Pablo Burset, Bo Lu, Shun Tamura, and Yukio Tanaka
Physical Review B 95, 224502-1-9 (Jun. 2017)
DOI: 10.1103/PhysRevB.95.224502

"Drude and Superconducting Weights and Mott Transitions in Variation Theory"
S. Tamura, H. Yokoyama
Journal of the Physical Society of Japan 84, 064707-1-11 (2015).
https://doi.org/10.7566/JPSJ.84.064707
*Editors' Choice

"Stability of staggered flux state in d-p model studied using variational Monte Carlo method"
S. Tamura, H. Yokoyama
Phys. Proc. 65, 1-4 (2015).
https://doi.org/10.1016/j.phpro.2015.05.092

"Variational Monte Carlo Study of Spin-Gapped Normal State and BCS-BEC Crossover in Two-Dimensional Attractive Hubbard Model"
S. Tamura, H. Yokoyama
Journal of the Physical Society of Japan 81, 064718-1-14 (Jun. 2012).
https://doi.org/10.1143/JPSJ.81.064718