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.
@article{arxiv.cond-mat/9603123,
title = {Renormalization-Group Approach to Spin-Wave Theory of Quantum Heisenberg Ferromagnet},
author = {Naoum Karchev},
journal= {arXiv preprint arXiv:cond-mat/9603123},
year = {2009}
}