Weyl Semimetallic State in the Rashba-Hubbard Model

TL;DR

This paper explores the emergence of Weyl points and helical edge states in a Rashba-Hubbard model, revealing how electron correlations influence Weyl point positions and examining weak magnetic order in the system.

Contribution

It introduces the Rashba-Hubbard model on a square lattice, demonstrating the presence of Weyl points and helical edge states, and analyzes correlation effects and magnetism.

Findings

Weyl points appear due to Rashba spin-orbit coupling.

Zero-energy helical edge states are observed with specific edge orientations.

Correlation effects can shift Weyl points toward the Fermi level.

Abstract

We investigate the Hubbard model with the Rashba spin-orbit coupling on a square lattice. The Rashba spin-orbit coupling generates two-dimensional Weyl points in the band dispersion. In a system with edges along [11] direction, zero-energy edge states appear, while no edge state exists for a system with edges along an axis direction. The zero-energy edge states with a certain momentum along the edges are predominantly in the up-spin state on the right edge, while they are predominantly in the down-spin state on the left edge. Thus, the zero-energy edge states are helical. By using a variational Monte Carlo method for finite Coulomb interaction cases, we find that the Weyl points can move toward the Fermi level by the correlation effects. We also investigate the magnetism of the model by the Hartree-Fock approximation and discuss weak magnetic order in the weak-coupling region.