Condensed Matter Seminar Series

Christoph Strunk

Universität Regensburg

Supercurrent diodes and squeezed vortices:
insights from inductance measurements

The recent discovery of intrinsic supercurrent diode effect [1], and its prompt observation in a rich variety of systems, has shown that nonreciprocal supercurrents naturally emerge when both space- and time-inversion symmetries are broken. I will report on  ac-manifestations of the 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 induc­tance 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-π-like transition in the current-phase relation. 
In a small perpendicular magnetic field, also the unpatterned heterostructure features a large inductance which results from the oscillations of pinned vortices around pinning centers. The vortex inductance is inversely proportional to the pinning potential. If a parallel field is applied in addition, the vortex inductance unexpectedly decreases in an anisotropic fashion. This observation can be under­stood as an anisotropic squeezing of the vortex cores, which is consequence of Lifschitz invariants in the free energy of our non-centro­sym­metric hetero­structure [3].

[1] F. Ando et al., Nature 584, 373 (2020)
[2] C. Baumgartner, et al., Nature Nanotech. 17, 39 (2022).
[3] L. Fuchs, et al., Phys. Rev. X 12, 041020 (2022)