Robust topological superconductivity in spin-orbit coupled systems at higher-order van Hove filling

TL;DR

This paper demonstrates that in spin-orbit coupled systems near higher-order van Hove fillings, chiral topological superconductivity emerges as a stable phase due to the interplay of VHSs and Berry phase effects, revealing new pathways for realizing topological states.

Contribution

It reveals how the interplay between van Hove singularities and Berry phase in a Rashba model leads to robust chiral topological superconductivity, a novel insight into correlated quantum materials.

Findings

Chiral p ± ip pairings are stable fixed points in the interaction space.

The nontrivial Berry phase induces hopping interactions that favor topological superconductivity.

Despite competing fluctuations, the system consistently favors topological pairing states.

Abstract

Van Hove singularities (VHSs) in proximity to the Fermi level promote electronic interactions and generate diverse competing instabilities. It is also known that a nontrivial Berry phase derived from spin-orbit coupling (SOC) can introduce an intriguing decoration into the interactions and thus alter correlated phenomena. However, it is unclear how and what type of new physics can emerge in a system featured by the interplay between VHSs and the Berry phase. Here, based on a general Rashba model on the square lattice, we comprehensively explore such an interplay and its significant influence on the competing electronic instabilities by performing a parquet renormalization group analysis. Despite the existence of a variety of comparable fluctuations in the particle-particle and particle-hole channels associated with higher-order VHSs, we find that the chiral $p \pm ip$ pairings emerge as two stable fixed trajectories within the generic interaction parameter space, namely the system becomes a robust topological superconductor. The chiral pairings stem from the hopping interaction induced by the nontrivial Berry phase. The possible experimental realization and implications are discussed. Our work sheds new light on the correlated states in quantum materials with strong SOC and offers fresh insights into the exploration of topological superconductivity.