Field-free superconducting diode effect and magnetochiral anisotropy in FeTe0.7Se0.3 junctions with the inherent asymmetric barrier

TL;DR

This study demonstrates a novel field-free superconducting diode effect and magnetochiral anisotropy in FeTe0.7Se0.3 junctions, achieved through an inherent asymmetric barrier, advancing superconducting electronics without complex fabrication.

Contribution

It introduces a simple method to realize field-free SDE and eMCA in FeTe0.7Se0.3 junctions using an inherent asymmetric barrier, avoiding complex fabrication or magnetic doping.

Findings

Field-free SDE observed in FeTe0.7Se0.3 junctions.

Presence of eMCA linked to spin-splitting from broken inversion symmetry.

Distinct temperature-dependent responses to magnetic fields.

Abstract

Nonreciprocal electrical transport, characterized by an asymmetric relationship between current and voltage, plays a crucial role in modern electronic industries. Recent studies have extended this phenomenon to superconductors, introducing the concept of the superconducting diode effect (SDE). The SDE is characterized by unequal critical supercurrents along opposite directions. Due to the requirement on broken inversion symmetry, the SDE is commonly accompanied by electrical magnetochiral anisotropy (eMCA) in the resistive state. Achieving a magnetic field-free SDE with field tunability is pivotal for advancements in superconductor devices. Conventionally, the field-free SDE has been achieved in Josephson junctions by intentionally intercalating an asymmetric barrier layer. Alternatively, internal magnetism was employed. Both approaches pose challenges in the selection of superconductors and fabrication processes, thereby impeding the development of SDE. Here, we present a field-free SDE in FeTe0.7Se0.3 (FTS) junction with eMCA, a phenomenon absent in FTS single nanosheets. The field-free property is associated with the presence of a gradient oxide layer on the upper surface of each FTS nanosheet, while the eMCA is linked to spin-splitting arising from the absence of inversion symmetry. Both the SDE and eMCA respond to magnetic fields with distinct temperature dependencies. This work presents a versatile and straightforward strategy for advancing superconducting electronics.