Model studies of topological phase transitions in materials with two types of magnetic atoms

TL;DR

This paper investigates Coulomb-induced topological phase transitions in triangular-lattice Hubbard models with two magnetic atom types, revealing a new class of transitions driven by virtual processes controlled by Coulomb interactions.

Contribution

It introduces a novel class of topological phase transitions induced by Coulomb engineering in magnetic lattice models, analyzed via the Schwinger boson method.

Findings

Topological phase transitions are triggered by second-order virtual processes.

Coulomb interactions control the transition strengths.

Potential realization in real magnetic materials.

Abstract

We study the topological phase transitions induced by Coulomb engineering in three triangular-lattice Hubbard models $AB_2$, $AC_3$ and $B_2C_3$, each of which consists of two types of magnetic atoms with opposite magnetic moments. The energy bands are calculated using the Schwinger boson method. We find that a topological phase transition can be triggered by the second-order (three-site) virtual processes between the two types of magnetic atoms, the strengths of which are controlled by the on-site Coulomb interaction $U$. This new class of topological phase transitions have been rarely studied and may be realized in a variety of real magnetic materials.