Magnetic domain dynamics in an insulating quantum ferromagnet

TL;DR

This study investigates magnetic avalanche behavior in an insulating quantum ferromagnet, revealing how temperature influences the symmetry and dynamics of Barkhausen noise without eddy-current effects.

Contribution

It provides the first analysis of Barkhausen noise in an insulating quantum ferromagnet, highlighting the role of local random fields and temperature-dependent dynamics.

Findings

Large avalanches near the Curie point show symmetric response without drag.

At low temperatures, drag effects emerge due to enhanced pinning.

Eddy currents are absent, isolating intrinsic magnetic dynamics.

Abstract

The statistics and form of avalanches in a driven system reveal the nature of the underlying energy landscape and dynamics. In conventional metallic ferromagnets, eddy-current back action can dominate the dynamics. Here, we study Barkhausen noise in Li(Ho,Y)F4, an insulating Ising ferromagnet that cannot sustain eddy currents. For large avalanches at temperatures approaching the Curie point, we find a symmetric response free of drag effects. In the low temperature limit, drag effects contribute to the dynamics, which we link to enhanced pinning from local random fields that are enabled by the microscopic dipole-coupled Hamiltonian (the Ising model in transverse field).