Intrinsic Superconducting Diode Effect

TL;DR

This paper proposes an intrinsic mechanism for the superconducting diode effect based on nonreciprocal depairing currents, revealing temperature-dependent behaviors and sign reversals influenced by magnetic fields in noncentrosymmetric superconductors.

Contribution

It introduces a new intrinsic mechanism for the superconducting diode effect, emphasizing the role of nonreciprocal depairing currents and their temperature and magnetic field dependencies.

Findings

Nonreciprocal depairing current scales with temperature near critical temperature.

Sign reversals of critical current occur with increasing magnetic field.

Nonreciprocity is linked to Landau critical momentum and helical superconductivity.

Abstract

Stimulated by the recent experiment [F. Ando et al., Nature 584, 373 (2020)], we propose an intrinsic mechanism to cause the superconducting diode effect (SDE). SDE refers to the nonreciprocity of the critical current for the metal-superconductor transition. Among various mechanisms for the critical current, the depairing current is known to be intrinsic to each material and has recently been observed in several superconducting systems. We clarify the temperature scaling of the nonreciprocal depairing current near the critical temperature and point out its significant enhancement at low temperatures. It is also found that the nonreciprocal critical current shows sign reversals upon increasing the magnetic field. These behaviors are understood by the nonreciprocity of the Landau critical momentum and the change in the nature of the helical superconductivity. The intrinsic SDE unveils the rich phase diagram and functionalities of noncentrosymmetric superconductors.