Topological Mott transition in a two band model of spinless fermions with on-site Coulomb repulsion

TL;DR

This paper investigates a topological Mott transition in a two-band model of spinless fermions with Coulomb repulsion and Rashba spin-orbit coupling, revealing a phase with Majorana states and a transition to a Mott insulator.

Contribution

It introduces a mean-field analysis of topological phases in a two-band spinless fermion model considering Coulomb and spin-orbit interactions, highlighting a new topological semimetal phase.

Findings

Identification of a topological semimetal phase induced by Rashba coupling.

Discovery of zero-energy Majorana states localized at boundaries.

Observation that Majorana states vanish at the Mott transition point.

Abstract

In the framework of mean field approach, we study topological Mott transition in a two band model of spinless fermions on a square lattice at half filling. We consider the combined effect of the on-site Coulomb repulsion and the spin-orbit Rashba coupling. The ground state phase diagram is calculated as a function of the strength of the spin-orbit Rashba coupling and the Coulomb repulsion. The spin-orbit Rashba coupling leads to a distinct phase of matter, the topological semimetal. We study a new type of phase transition between the non-topological insulator and topological semimetal states. Topological phase state is characterized by the zero energy Majorana states, which there are in defined region of the wave vectors and are localized at the boundaries of the sample. The region of existence of the zero energy Majorana states tends to zero at the point of the Mott phase transition. The zero energy Majorana states are dispersionless (they can be considered as flat bands), the Chern number and Hall conductance are equal to zero (note in two dimensional model