Magnon Nesting in Driven Two-Dimensional Quantum Magnets

TL;DR

This paper reveals a novel non-equilibrium dynamical instability in driven two-dimensional quantum magnets, leading to enhanced antiferromagnetic correlations via a magnon nesting mechanism, distinct from classical and thermal instabilities.

Contribution

It introduces a new quantum instability mechanism in driven magnets, characterized by frequency-tuned magnon nesting and emergent antiferromagnetic correlations, not accessible in thermal equilibrium.

Findings

Discovery of a non-equilibrium magnon nesting instability.

Emergence of enhanced antiferromagnetic correlations.

Distinct quantum mechanical origin from classical instabilities.

Abstract

We uncover a new class of dynamical quantum instability in driven magnets leading to emergent enhancement of antiferromagnetic correlations even for purely ferromagnetic microscopic couplings. A primary parametric amplification creates a frequency-tuned nested magnon distribution in momentum space, which seeds a secondary instability marked by the emergence of enhanced antiferromagnetic correlations, mirroring the instability of nested Fermi surfaces in electronic systems. In sharp contrast to the fermionic case, however, the magnon-driven instability is intrinsically non-equilibrium and fundamentally inaccessible in thermal physics. Its quantum mechanical origin sets it apart from classical instabilities such as Faraday and modulation instabilities, which underlie several instances of dynamical behavior observed in magnetic and cold-atom systems.