Higher-order Topological States in Chiral Split Magnons of Honeycomb Altermagnets

TL;DR

This paper theoretically investigates higher-order topological magnons in honeycomb altermagnets, revealing localized corner modes and propagating hinge excitations with potential applications in quantum computing and energy-efficient information transfer.

Contribution

It introduces a novel theoretical framework combining altermagnetism and higher-order topology to identify and analyze unconventional magnon states with symmetry-protected properties.

Findings

Identification of second-order topological magnon insulators.

Discovery of anisotropic surface states and hinge modes.

Potential for manipulating magnons in quantum devices.

Abstract

We theoretically explore higher-order topological magnons in collinear altermagnets, encompassing a dimensional hierarchy ranging from localized corner modes to propagating hinge excitations. By employing antiferromagnetic interlayer coupling in bosonic Bogoliubov-de Gennes Hamiltonian, our work reveals anisotropic surface states and spatially distributed hinge modes propagating along facet intersections. We track the adiabatic evolution of Wannier centers to identify the bulk-polarization with second-order topological magnon insulator, where various magnon spectra demonstrate symmetry-protected band structure beyond conventional topology. Leveraging the stability and propagative properties of hinge modes, these unconventional magnons demonstrate manipulability in atomic-scale modifications of termination. Our study integrate altermagnetism with higher-order topology, which advance magnon-based quantum computing processing energy-efficient integrated architectures and information transfer.