Non-reciprocity in superconductors - Josephson diode effect and beyond

The recent discovery of intrinsic supercurrent diode effect [1], and its prompt observation in a rich variety of systems, as shown that nonreciprocal supercurrents naturally emerge when both space- and time-inversion symmetries are broken. I will report on both dc and ac-manifestations of the Josephson diode effect in the non-linear inductance in planar Josephson junctions, based on a ballistic Al/InAs-heterostructure that is exposed to an in-plane magnetic field Bip [2]. At low Bip a non-reciprocal term is found in the induc¬tance that is linear in Bip. At higher Bip a sign reversal of the magnetochiral term is observed that can be traced back to a 0-pi-like transition in the current-phase relation [3]. Different
avenues for a theoretical interpretation are discussed. As pronounced date tunability of both the phi_0 shift and the diode efficiency in an asymmetric SQUID device demonstrates that Rashba spin-orbit interaction provides a substantial contribution to the Josephson diode effect [4].

[1] F. Ando et al., Nature 584, 373 (2020).
[2] C. Baumgartner et al., Nature Nanotech. 17, 39 (2022).
[3] C. Baumgartner et al., Nature Nanotech. 18, 1266
(2023).
[4] S. Reinhardt et al., Nature Commun. 15, 4413 (2024).