Phase-ordering dynamics in itinerant quantum ferromagnets

TL;DR

This paper investigates the unique phase-ordering dynamics in itinerant quantum ferromagnets, revealing non-classical growth laws and anomalous behaviors due to quantum fluctuation effects affecting domain coarsening.

Contribution

It introduces a comprehensive analysis of quantum fluctuation effects on phase ordering, deriving new growth laws and scaling behaviors for quantum ferromagnets after quenches.

Findings

Transient regime with different power-law growth

Anomalous magnetization dependence in long-time behavior

Non-power-law growth at quantum critical point

Abstract

The phase-ordering dynamics that result from domain coarsening are considered for itinerant quantum ferromagnets. The fluctuation effects that invalidate the Hertz theory of the quantum phase transition also affect the phase ordering. For a quench into the ordered phase a transient regime appears, where the domain growth follows a different power law than in the classical case, and for asymptotically long times the prefactor of the t^{1/2} growth law has an anomalous magnetization dependence. A quench to the quantum critical point results in a growth law that is not a power-law function of time. Both phenomenological scaling arguments and renormalization-group arguments are given to derive these results, and estimates of experimentally relevant length and time scales are presented.