Superconducting diode effect and large magnetochiral anisotropy in Td -MoTe2 thin film

Abstract

In the absence of time-reversal invariance, metals without inversion symmetry may exhibit nonreciprocal charge transport—a magnetochiral anisotropy that manifests as unequal electrical resistance for opposite current flow directions. If superconductivity also sets in, then the charge transmission may become dissipationless in one direction while remaining dissipative in the opposite, thereby realizing a superconducting diode. Through both direct-current and alternating-current measurements, we study the nonreciprocal effects in thin films of the noncentrosymmetric superconductor Td−MoTe2 with disorder. We observe nonreciprocal superconducting critical currents with a diode efficiency close to 20%, and a large magnetochiral anisotropy coefficient up to 5.9×108T−1A−1, under weak out-of-plane magnetic field in the millitesla range. The great enhancement of rectification efficiency under out-of-plane magnetic field is likely ascribed to the vortex ratchet effect, which naturally appears in the noncentrosymmetric superconductor with disorder. Intriguingly, unlike the finding in Rashba systems, the strongest in-plane nonreciprocal effect does not occur when the field is perpendicular to the current flow direction. We develop a phenomenological theory to demonstrate that this peculiar behavior can be attributed to the asymmetric structure of spin-orbit coupling in Td−MoTe2. Our study highlights how the crystallographic symmetry critically impacts the nonreciprocal transport, and would further advance the research for designing the superconducting diode with the best performance.

Source-reported materials — not catalogue approval

Similar papers