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

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.