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

J Herbrych,G Alvarez,M Mierzejewski,M Środa,E Dagotto

doi:10.1038/s41467-021-23261-2

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.

Highlights

Topological phases of matter are among the most intriguing research directions in Condensed Matter Physics
In order to fully take into account the many-body nature of the orbital-selective Mott phase (OSMP) system, we have developed a hybrid algorithm, the details of which are given in the “Methods” section
We found that the resulting amplitude Δ‘ 1⁄4 ÀVΔB‘0CS is almost uniform within the OSMP chain

Summary

Introduction

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 condensedmatter compounds. The key ingredient in systems expected to host the MZM28 is the presence of an SC gap, modeled typically by an s-wave pairing field Such a term represents the proximity effect[29] induced on the magnetic system by an external s-wave superconductor. In the class of systems studied here (low-dimensional OSMP iron-based materials), the pairing tendencies could arise from the intrinsic superconductivity of BaFe2S3 and BaFe2Se3 under pressure[31,32,33] or doping[22,34]

Methods

Results

Conclusion