Quantum description of spherical spins
Condensed Matter
2009-10-22 v3
Abstract
The spherical model for spins describes ferromagnetic phase transitions well, but it fails at low temperatures. A quantum version of the spherical model is proposed. It does not induce qualitative changes near the phase transition. However, it produces a physical low temperature behavior. The entropy is non-negative. Model parameters can be adapted to the description of real quantum spins. Several applications are discussed. Zero-temperature quantum phase transitions are analyzed for a ferromagnet and a spin glass in a transversal field. Their crossover exponents are presented.
Cite
@article{arxiv.cond-mat/9408055,
title = {Quantum description of spherical spins},
author = {Th. M. Nieuwenhuizen},
journal= {arXiv preprint arXiv:cond-mat/9408055},
year = {2009}
}
Comments
4 pages postscript. Revised version, to appear in Phys. Rev. Lett