Title: [NCTS IAC Lecture] Nonreciprocal transport and diode effect in superconductors
Speaker: Prof. Naoto Nagaosa (RIKEN)
Time: 2023/6/19 (Mon.) 10:30-11:30
Place: NCTS Physics Lecture Hall, 4F, Chee-Chun Leung Cosmology Hall, NTU
Online: https://nationaltaiwanuniversity-zbh.my.webex.com/nationaltaiwanuniversity-zbh.my/j.php?MTID=m5021d765b80c5f988c040c430c822fd7

Abstract:
Nonreciprocal transport (NRT) in noncentrosymmetric quantum materials attracts lot of interest [1]. Time-reversal symmetry and inversion symmetry are relevant to NRT, and the magnetic field induced NRT is usually a small effect in metals and semiconductors since it requires the spin-orbit interaction and Zeeman effect [1]. However, it is enhanced once the superconductivity sets in, which introduces a small energy scale, i.e., the superconducting gap, below which the bosonic transport dominates. I will discuss recent progress in this issue, i.e., the NRT and diode effect in superconductors especially in two-dimensions and quasi-one dimension. It includes the resistive states where the fluctuation of the superconducting order parameter gives the paraconductivity [2], the nonreciprocal resistivity dominated by vortex motion [3], nonreciprocal Josephson junction [4], phenomenological thery of superconducting diode effect [5], and geometric origin of NRT in nano-tube superconductors [6].

[1] Y.Tokura, and N. Nagaosa, Nat. Commun. 9 3740 (2018).
[2] R. Wakatsuki at al., Sci. Adv. 3 e1602390 (2017)
[3] K. Yasuda et al., Nat. Commun. 10 2734 (2019)
[4] K. Misaki and N. Nagaosa, Rev. B 103 245302 (2021)
[5] James Jun He, Yukio Tanaka, Naoto Nagaosa, New J. Phys. 24 053014 (2022)
[6] James Jun He, Yukio Tanaka, Naoto Nagaosa, arXiv:2212.02183.