Interaction-induced topological phase transition and Majorana edge states in low-dimensional orbital-selective Mott insulators

TL;DR

This paper demonstrates that in low-dimensional orbital-selective Mott insulators, Coulomb interactions can induce a topological phase transition, leading to Majorana edge states in a superconductor with spiral spin order.

Contribution

It reveals that Coulomb interactions can drive a superconductor into a topological state with Majorana modes, a novel mechanism in orbital-selective Mott insulators.

Findings

Coulomb interaction induces topological phase transition.

Majorana fermions appear at system edges.

Spiral spin order coexists with topological superconductivity.

Abstract

Topological phases of matter are among the most intriguing research directions in Condensed Matter Physics. It is known that superconductivity induced on a topological insulator's surface can lead to exotic Majorana modes, the main ingredient of many proposed quantum computation schemes. In this context, the iron-based high critical temperature superconductors are a promising platform to host such an exotic phenomenon in real condensed-matter compounds. The Coulomb interaction is commonly believed to be vital for the magnetic and superconducting properties of these systems. This work bridges these two perspectives and shows that the Coulomb interaction can also drive a canonical superconductor with orbital degrees of freedom into the topological state. Namely, we show that above a critical value of the Hubbard interaction the system simultaneously develops spiral spin order, a highly unusual triplet amplitude in superconductivity, and, remarkably, Majorana fermions at the edges of the system.