Time-dependent strain-tuning topological magnon phase transition

TL;DR

This paper investigates how time-dependent strains in honeycomb lattice magnets can induce topological magnon phases through Floquet theory, revealing new ways to control magnon spectra and topological transitions.

Contribution

It introduces a Floquet-based approach to analyze strain-induced topological magnon phase transitions, highlighting the role of uniform and nonuniform strains in magnon manipulation.

Findings

Homogeneous strains induce topologically protected magnon phases.

Certain uniform strains mimic Dzyaloshinskii-Moriya interactions.

Nonuniform strains can confine magnon states along specific directions.

Abstract

Collinear magnets in honeycomb lattices under the action of time-dependent strains are investigated. Given the limits of high-frequency periodically varying deformations, we derive an effective Floquet theory for spin system that results in the emergence of a spin chirality. We find that the coupling between magnons and spin chirality depends on the details of the strain such as the spatial dependence and applied direction. Magnonic fluctuations about the ferromagnetic state are determined, and it is found that spatially homogeneous strains drive the magnon system into topologically protected phases. In particular, we show that certain uniform strain fields play the role of an out-of-plane next-neighbor Dzyaloshinskii-Moriya interaction. Furthermore, we explore the application of nonuniform strains, which lead to a confinement of magnon states that for uniaxial strains, propagates along the direction that preserves translational symmetry. Our work demonstrates a direct and novel way in which to manipulate the magnon spectrum based on time-dependent strain engineering that is relevant for exploring topological transitions in quantum magnonics.