Helical glasses near ferromagnetic quantum criticality

TL;DR

This paper investigates how quenched charge disorder affects the magnetic phase transitions near ferromagnetic quantum critical points, revealing disorder-induced destabilization of ferromagnetism and promotion of spiral magnetic order with complex correlation behaviors.

Contribution

It introduces a combined approach of replica disorder averaging and quantum order-by-disorder to analyze disorder effects on magnetic phases near quantum criticality.

Findings

Weak disorder destabilizes ferromagnetic order.

Disorder enhances susceptibility to spiral magnetic phases.

Disorder induces vortex lines and short-range correlations in the spiral phase.

Abstract

We study the effects of quenched charge disorder on the phase reconstruction near itinerant ferromagnetic quantum critical points in three spatial dimensions. Combining a replica disorder average with a fermionic version of the quantum order-by-disorder mechanism, we show that weak disorder destabilizes the ferromagnetic state and enhances the susceptibility towards incommensurate, spiral magnetic ordering. The Goldstone modes of the spiral phase are governed by a 3d-XY model. The induced disorder in the pitch of the spiral generates a random anisotropy for the Goldstone modes, inducing vortex lines in the phase of the helical order and rendering the magnetic correlations short ranged with a strongly anisotropic correlation length.