Triplet superconductivity in the Rashba$^4$ model

TL;DR

This paper investigates a lattice model with multiple Rashba band crossings, revealing that inter-point scattering induces an unconventional triplet superconductivity near the band crossing points.

Contribution

It introduces the Rashba$^4$ model with multiple band crossings and demonstrates the emergence of a novel triplet superconducting state driven by inter-point scattering.

Findings

Inter-point scattering leads to unconventional triplet superconductivity.

Superconductivity occurs when the Fermi energy is near the Rashba band crossings.

The model reveals new pairing mechanisms not present in single Rashba point systems.

Abstract

The Rashba$^4$ model is a lattice model of interacting fermions with a tight-binding dispersion relation that exhibits four Rashba band crossing points at the same energy. The fermions interact weakly, by an on-site repulsion and an additional nearest-neighbour two-body interaction, which may be attractive or repulsive. We study this model when the Fermi energy is at or close to the band crossings, by a combination of renormalization group flow equations and mean-field theory. We find that the scattering processes between different Rashba points drive superconductivity of an unusual triplet type not found in models with a single Rashba point.