Model Hamiltonian for Altermagnetic Topological Insulators

TL;DR

This paper develops models of altermagnetic topological insulators that combine magnetic symmetry with topological properties, revealing new boundary states and providing a framework for spintronic applications without net magnetization.

Contribution

It introduces theoretical models of altermagnetic topological insulators with symmetry-protected boundary modes, linking altermagnetism and topological quantum matter.

Findings

Spin Chern number is a robust topological invariant in 2D.

Topological phases support boundary modes like corners, hinges, and surfaces.

Framework enables engineering of spintronic systems without net magnetization.

Abstract

We present models of topological insulating Hamiltonians exhibiting intrinsic altermagnetic features, protected by combined three-fold or four-fold rotational symmetries with time-reversal. We demonstrate that the spin Chern number serves as a robust topological invariant in two-dimensional systems, while for three-dimensional structures, the topological nature is characterized by the spin Chern numbers computed on the $k_z$=$0$ and $k_z$=$\pi$ planes. The resulting phases support symmetry-protected boundary modes, including corner, hinges and surface states, whose structure is determined by the magnetic symmetry and the local magnetic moments. Our findings bridge the fields of altermagnetism and topological quantum matter, and establish a theoretical framework for engineering spintronic topological systems without net magnetization.