Theory of helimagnons in itinerant quantum systems II: Nonanalytic corrections to Fermi-liquid behavior

Abstract

A recent theory for the ordered phase of helical or chiral magnets such as MnSi is used to calculate observable consequences of the helical Goldstone modes or helimagnons. In systems with no quenched disorder, the helimagnon contributions to the specific heat coefficient is shown to have a linear temperature dependence, while the quasi-particle inelastic scattering rate is anisotropic in momentum space and depends on the electronic dispersion relation. For cubic lattices the generic temperature dependence is given by a non-Fermi-liquid T^(3/2) behavior. The contribution to the temperature dependence of the resistivity is shown to be T^(5/2) in a Boltzmann approximation. The helimagnon thus leads to nonanalytic corrections to Fermi-liquid behavior. Implications for experiments, and for transport theories beyond the Boltzmann level, are discussed.