Rashba spin-orbit coupling in the square lattice Hubbard model: A truncated-unity functional renormalization group study

TL;DR

This study investigates how Rashba spin-orbit coupling influences magnetic and superconducting phases in the square lattice Hubbard model, revealing phase competition and pairing mixing effects using a specialized functional renormalization group approach.

Contribution

It introduces a truncated-unity functional renormalization group method to analyze magnetic and superconducting instabilities in the Rashba-Hubbard model, highlighting phase diagrams and pairing mixing.

Findings

Identification of magnetic and superconducting phases

Quantification of singlet-triplet pairing mixing

Phase diagrams depending on coupling strengths

Abstract

The Rashba-Hubbard model on the square lattice is the paradigmatic case for studying the effect of spin-orbit coupling, which breaks spin and inversion symmetry, in a correlated electron system. We employ a truncated-unity variant of the functional renormalization group which allows us to analyze magnetic and superconducting instabilities on equal footing. We derive phase diagrams depending on the strengths of Rasbha spin-orbit coupling, real second-neighbor hopping and electron filling. We find commensurate and incommensurate magnetic phases which compete with d-wave superconductivity. Due to the breaking of inversion symmetry, singlet and triplet components mix; we quantify the mixing of d-wave singlet pairing with f-wave triplet pairing.