Nonreciprocity of supercurrent along applied magnetic field

TL;DR

This paper investigates the emergence of nonreciprocal supercurrents along an applied magnetic field in superconductors, revealing that vortex orientation induces symmetry breaking enabling such nonreciprocity, aligning with recent experimental findings.

Contribution

It introduces a theoretical model showing how vortex axis orientation causes nonreciprocal supercurrents along magnetic fields, extending symmetry considerations in superconductivity.

Findings

Nonreciprocal critical currents are enabled by vortex axis orientation.

London's equations describe the Meissner response and nonreciprocity.

The model aligns with recent experimental observations.

Abstract

Nonreciprocal current responses arise in a broad range of systems, from magnons and phonons to supercurrents, due to an interplay between spatial and temporal symmetry breakings. These find applications in devices, such as circulators and rectifiers, as well as in probing the interactions and states that underlie the nonreciprocity. An established symmetry argument anticipates emergence of nonreciprocal currents along a direction perpendicular to the applied magnetic field that breaks the time-reversal symmetry. Here, motivated by recent experiments, we examine the emergence of nonreciprocity in vortex-limited superconducting critical currents along an applied magnetic field. Employing London's equations for describing the Meissner response of a superconducting film, we find that an additional symmetry breaking due to a preferred vortex axis enables nonreciprocal critical currents along the applied magnetic field, consistent with the so far unexplained experimental observation. Building on our concrete theoretical model for supercurrents, we discuss a possible generalization of the prevailing symmetry consideration to encompass nonreciprocal currents along the time-reversal symmetry breaking direction.