Discrete time crystal made of topological edge magnons

TL;DR

This paper demonstrates the emergence of a discrete time crystal in topological edge magnons of a Heisenberg ferromagnet under external driving, revealing spontaneous symmetry breaking and proposing experimental detection methods.

Contribution

It presents the first realization of time crystals at topological edge states in a bosonic system, expanding the understanding of time crystalline phases.

Findings

Time-crystalline behavior observed in magnon edge states

Spontaneous breaking of discrete time-translational symmetry

Potential experimental signatures identified

Abstract

We report the emergence of time-crystalline behavior in the \pi-Berry phase protected edge states of a Heisenberg ferromagnet in the presence of an external driving field. The magnon amplification due to the external field spontaneously breaks the discrete time-translational symmetry, resulting in a discrete time crystal with a period that is twice that of the applied EM field. We discuss the nature and symmetry protection of the time crystalline edge states and their stability against various perturbations that are expected in real quantum magnets. We propose an experimental signature to unambiguously detect the time crystalline behavior and identify two recently discovered quasi-2D magnets as potential hosts. We present a first-of-its-kind realization of time crystals at topological edge states, which can be generalized and extrapolated to other bosonic quasi-particle systems that exhibit parametric pumping and topological edge states.