Tunable SSH model in ferromagnetic systems

TL;DR

This paper introduces a new four-band model called DISSH, extending the SSH model into ferromagnetic systems by leveraging magnetic symmetries, and demonstrates how to control its topological phases through magnetic moment tuning.

Contribution

The paper proposes the DISSH model, a four-band extension of SSH model based on magnetic symmetries, applicable to ferromagnetic systems, and shows how to manipulate its topological phases experimentally.

Findings

DISSH model can be block diagonalized into two SSH-like models.

Topological phases of DISSH can be tuned by adjusting magnetic moments.

The model extends SSH topological concepts into ferromagnetic materials.

Abstract

It is well known that the topology of Su-Schrieffer-Heeger(SSH) model, which belongs to AIII symmetry class, is protected by chiral symmetry. In this article, instead of chiral symmetry, we constrain the bulk Hamiltonian by a magnetic point group symmetry, which can be generated by a unitary symmetry and an anti-unitary symmetry. Under these symmetries, a four-band model can be block diagonalized into two 2-band models and each 2-band model is analogous to an SSH model. As the two 2-band models are individual, we call the four-band model double independent SSH (DISSH) model. Interestingly, since the symmetry requirements of DISSH model can be fulfilled in ferromagnetic systems, the discovery in this manuscript extends SSH model into ferromagnetic systems. Furthermore, we presented an example of DISSH model with a set of reasonable parameters to show that it is possible to manipulate the topological phase of DISSH model by tuning the magnetic moment in experiment.