Topological superconductivity and superconducting diode effect mediated via unconventional magnet and Ising spin-orbit coupling

TL;DR

This paper presents a theoretical model demonstrating how unconventional magnetic order and spin-orbit couplings in a 1D system can realize topological superconductivity and a significant superconducting diode effect with high efficiency.

Contribution

It introduces a novel 1D model combining magnetic order and spin-orbit interactions to achieve topological superconductivity and intrinsic diode effects, supported by self-consistent mean-field analysis.

Findings

Both BCS and FFLO pairing states support topological superconductivity with Majorana modes.

The FFLO state induces a field-free superconducting diode effect with diode efficiency around 65%.

The model provides a pathway for realizing topological superconductors and efficient superconducting diodes.

Abstract

We propose a theoretical framework in which a one-dimensional (1D) tight-binding model incorporating unconventional magnetic order together with Rashba and Ising spin-orbit couplings are considered to realize two key phenomena in condensed matter systems: topological superconductivity and the superconducting diode effect (SDE). We first elucidate the underlying band topology of the normal-state Hamiltonian and subsequently introduce an on-site attractive Hubbard interaction. Performing a a self-consistent mean-field analysis, we establish superconducting order parameters in both the conventional Bardeen-Cooper-Schrieffer (BCS) and finite-momentum Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) pairing channels. Intriguingly, both pairing states can support topological superconductivity, characterized by a nontrivial winding number, and lead to the emergence of four zero-energy Majorana modes localized at the ends of the 1D chain. The FFLO state further gives rise to an intrinsic field-free SDE, manifested as a nonreciprocal supercurrent and quantified by the diode efficiency $\eta$. Notably, our model yields a large diode efficiency $\eta \sim 65\%$, highlighting its potential for realising topological superconductivity and highly efficient superconducting devices.