Renormalization-Group Approach to Spin-Wave Theory of Quantum Heisenberg Ferromagnet

TL;DR

This paper applies a renormalization-group approach to analyze the low-temperature properties of a 2D quantum Heisenberg ferromagnet, deriving recursion equations and revealing differences from traditional spin-wave theory for small spins.

Contribution

It introduces a renormalization-group method with recursion equations to study low-temperature behavior, providing new insights for small spin values.

Findings

Derived recursion equations in one-loop approximation

Obtained low-temperature asymptotics of correlation length and susceptibility

Found significant differences from spin-wave theory for small spins

Abstract

The renormalization-group method is used to analyze the low-temperature behaviour of a two-dimentional, spin-$s$ quantum Heisenberg ferromagnet. A set of recursion equations is derived in an one-loop approximation. The low-temperature asymptotics of the correlation length and the uniform susceptibility are obtained. For small spins ($s= 1/2,1$) the results are essentially different from those in the spin-wave theory.