Slow Equilibrium Relaxation in a Chiral Magnet Mediated by Topological Defects

TL;DR

This study investigates the slow relaxation dynamics of non-collinear magnetic orders in a chiral magnet, revealing that topological defects like emergent monopoles significantly prolong the stabilization process after perturbation.

Contribution

It provides the first experimental measurement of the lifetime of topological defects in a non-collinear magnetic system, linking slow relaxation to defect formation and dissipation.

Findings

Relaxation time of ~0.2 s after perturbation

Slower than typical nanosecond micromagnetic timescales

Topological defects like emergent monopoles govern slow dynamics

Abstract

We performed a pump-probe experiment on the chiral magnet Cu$_2$OSeO$_3$ to study the relaxation dynamics of its non-collinear magnetic orders, employing a millisecond magnetic field pulse as the pump and resonant elastic x-ray scattering as the probe. Our findings reveal that the system requires $\sim$0.2 s to stabilize after the perturbation applied to both the conical and skyrmion lattice phase; significantly slower than the typical nanosecond timescale observed in micromagnetics. This prolonged relaxation is attributed to the formation and slow dissipation of local topological defects, such as emergent monopoles. By unveiling the experimental lifetime of these emergent singularities in a non-collinear magnetic system, our study highlights a universal relaxation mechanism in solitonic textures within the slow dynamics regime, offering new insights into topological physics and advanced information storage solutions.