Chirality-induced pseudo-magnetic fields, flat bands and enhancement of superconductivity

TL;DR

This paper explores how chiral spin textures induce pseudo-magnetic fields that can enhance superconductivity by creating flat Landau levels, leading to unique quasiparticle signatures and robust pairing states.

Contribution

It introduces a mechanism where chiral spin textures generate pseudo-magnetic fields that promote superconductivity through flat band formation and novel pairing states.

Findings

Superconductivity can be enhanced by flat Landau levels induced by pseudo-magnetic fields.

The dominant pairing is identified as an s-wave pair density wave of FFLO type.

Distinct signatures include flat bands of Bogoliubov quasiparticles and Landau level resonances.

Abstract

Systems in which exchange interactions couple carrier spins to a spin texture with a net chirality exhibit a spin-dependent Aharonov-Bohm effect, where the geometric gauge field and pseudo-magnetic field have opposite signs for carriers with opposite spins. As a result, Cooper pairs see a net zero vector potential and superconducting pairing is not hindered by pair-breaking effects. This allows superconductivity to occur even when the geometric field induces quantized Landau levels. We identify the dominant pairing order as an s-wave pair density wave of an FFLO type. Flat Landau levels can significantly enhance superconducting $T_c$, favoring superconductivity over competing orders. This exotic paired state features tell-tale signatures such as flat bands of Bogoliubov-deGennes quasiparticles, manifest through Landau level-like resonances in the quasiparticle density of states.