Quantum critical behavior of disordered itinerant ferromagnets

TL;DR

This paper investigates the quantum critical behavior of disordered itinerant ferromagnets at zero temperature, revealing unique scaling laws and critical exponents influenced by disorder-induced long-range interactions.

Contribution

It provides an exact analysis of the quantum critical point in disordered itinerant ferromagnets, highlighting the impact of disorder on critical exponents and scaling behavior.

Findings

Quantum critical exponents differ from finite temperature values in 3D.

Disorder induces long-range interactions affecting critical behavior.

Predictions are proposed for experimental verification.

Abstract

The quantum ferromagnetic transition at zero temperature in disordered itinerant electron systems is considered. Nonmagnetic quenched disorder leads to diffusive electron dynamics that induces an effective long-range interaction between the spin or order parameter fluctuations of the form r^{2-2d}, with d the spatial dimension. This leads to unusual scaling behavior at the quantum critical point, which is determined exactly. In three-dimensional systems the quantum critical exponents are substantially different from their finite temperature counterparts, a difference that should be easily observable. Experiments to check these predictions are proposed.