Exciting terahertz magnons with amplitude modulated light: spin pumping, squeezed states, symmetry breaking and pattern formation

TL;DR

This paper introduces Modulated Floquet Parametric Driving (MFPD), a novel method to excite and control high-frequency antiferromagnetic resonances and spin patterns using amplitude modulated light, revealing new quantum and symmetry-breaking phenomena.

Contribution

The study presents MFPD as a new technique to access THz-range antiferromagnetic resonances and induce complex spin dynamics, including entangled magnon pairs and symmetry-breaking states.

Findings

Demonstration of parametric excitation of THz antiferromagnetic resonances via optical signals.

Observation of entangled two-mode squeezed magnon pairs in anisotropic antiferromagnets.

Induction of symmetry-breaking steady states with resonant magnon pairs and spin pattern formation.

Abstract

We show how amplitude modulated, coherent high-frequency drives can be used to access otherwise difficult to reach collective resonances and off-resonantly induce parametric instabilities. In particular, we demonstrate that difficult to access antiferromagnetic resonances in the THz range can be parametrically excited with signals at optical frequencies via a mechanism that we call Modulated Floquet Parametric Driving (MFPD). We study spin pumping and the formation of entangled, two-mode squeezed magnon pairs in anisotropic antiferromagnets under MFPD. Furthermore, we show that MFPD induces transitions to symmetry breaking steady-states in which dynamical spin patterns are formed by resonant magnon pairs.