Bose-Einstein condensation of magnons

TL;DR

This paper investigates the Bose-Einstein condensation of magnons in three-dimensional spin systems using the Renormalization Group method, revealing a different temperature dependence of the critical field than previous models, and discusses quantum critical phenomena.

Contribution

The study introduces a Renormalization Group approach to analyze magnon BEC, providing a new temperature dependence of the critical field contrasting earlier Hartree-Fock-Popov results.

Findings

Critical field varies as T^2 near zero temperature.

The RG results differ from previous T^{3/2} dependence.

Discussion of quantum critical phenomena explains the difference.

Abstract

We use the Renormalization Group method to study the Bose-Einstein condensation of the interacting dilute magnons which appears in three dimensional spin systems in magnetic field. The obtained temperature dependence of the critical field $H_c(T)-H_c(0) \sim T^{2}$ is different from the recent self-consistent Hartree-Fock-Popov calculations (cond-mat/0405422) in which a $T^{3/2}$ dependence was reported . The origin of this difference is discussed in the framework of quantum critical phenomena.