Field-free superconducting diode effect in layered superconductor FeSe

TL;DR

This paper reports the discovery of a field-free superconducting diode effect in layered FeSe, revealing that symmetry breaking and thermoelectric effects enable nonreciprocal zero-resistance states without magnetic fields.

Contribution

It demonstrates the existence of a field-free superconducting diode effect in FeSe and clarifies its physics involving thermoelectric response and geometrical asymmetry.

Findings

Field-free SDE observed in FeSe.

Thermoelectric response contributes to SDE.

Geometrical asymmetry influences diode behavior.

Abstract

The superconducting diode effect (SDE), where zero-resistance states appear nonreciprocally during current injection, is receiving tremendous interest in both fundamental and applied physics because the SDE is a novel manifestation of symmetry breaking and enables the creation of a novel diode. In particular, magnetic-field-free SDEs have been extensively investigated because of their potential to serve as building blocks for superconducting circuit technology. In this letter, we report the field-free SDE in a layered superconductor, FeSe. Its underlying physics is clarified by systematic controlled experiments to be an interplay of a large thermoelectric response and geometrical asymmetry in FeSe. Our findings can pave a new avenue for the construction of novel material and device platforms utilizing SDEs.