Field-free Josephson diode effect in a d-wave superconductor heterostructure

TL;DR

This paper demonstrates how a Josephson diode effect can be achieved without magnetic fields in d-wave superconductor heterostructures, revealing new ways to identify unconventional superconducting pairings.

Contribution

It shows that a large, field-free Josephson diode effect can be realized in d-wave superconductor heterostructures by breaking specific symmetries, expanding understanding of superconducting junctions.

Findings

The diode effect can be tuned by magnetic field, gate voltage, and junction length.

Large field-free diode effect occurs by breaking {\

Edge states in chiral d + id' superconductors influence the diode effect.

Abstract

We study superconductor/normal region/superconductor (S|N|S) Josephson junction formed using superconductors with d, d + id', and d + is superconducting pairings. We show that the quality factor of the Josephson diode effect and its sign can be substantially tuned by the external magnetic field, gate voltage, and the length of the junction for all three types of pairings. We also identify the conditions under which the anomalous Josephson and Josephson diode effects can appear in the junction by analyzing appropriate symmetries. In particular, by breaking a {\pi}-rotation symmetry, we show how a large field-free Josephson diode effect can be realized even in the absence of spin-orbit coupling. We also study the role of edge states appearing in the case of chiral superconductor with d + id' pairing. Our results demonstrate that the Josephson diode effect in a planar geometry can be used as a signature of unconventional superconducting pairings.