Nonanalytic Corrections to Fermi-Liquid Behavior in Helimagnets

TL;DR

This paper investigates the anisotropic Goldstone mode in helimagnets and demonstrates how it causes nonanalytic temperature-dependent corrections to Fermi-liquid properties, affecting specific heat, resistivity, and quasiparticle lifetime.

Contribution

It identifies the anisotropic Goldstone mode in helimagnets and shows its role in producing nonanalytic corrections to Fermi-liquid behavior.

Findings

T-linear correction to specific heat coefficient

T^{5/2} correction to resistivity

Anisotropic quasiparticle lifetime behavior

Abstract

The Goldstone mode in the ordered phase of itinerant helimagnets, such as MnSi or FeGe, is determined and shown to have a strongly anisotropic dispersion relation. The softness of this mode is, in a well-defined sense, in between that of ferromagnetic and antiferromagnetic magnons, respectively. It is shown that this soft mode leads to nonanalytic corrections to Fermi-liquid behavior, with a T-contribution to the specific heat coefficient, and a T^{5/2}-contribution to the resistivity. The quasi-particle inelastic lifetime shows anisotropic behavior in momentum space.