DOI: https://doi.org/10.30970/jps.03.370
QUANTUM FLUCTUATIONS IN CUBIC FERROMAGNETS
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Journal of Physical Studies 3(3), 370–376 (1999)
DOI: https://doi.org/10.30970/jps.03.370 QUANTUM FLUCTUATIONS IN CUBIC FERROMAGNETS |
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J. Sznajd, M. Dudziński
Institute of Low Temperature and Structure Research,
Polish Academy of Sciences,
50-950 Wroc\law, Poland
The theory of phase transitions in quantum spin ferromagnets with cubic single ion anisotropy is reviewed. Some fundamental difficulties with the mean–field approach to these systems are discussed. It is pointed out that quantum fluctuations drive the quadrupolar long range order in cubic ferromagnets with three easy axes. This order cannot be observed in the classical counterpart of the considered model. A new decimation procedure to study magnetic chains with multi–spin interaction is proposed and applied to investigate effective Hamiltonian of the cubic ferromagnet with large anisotropy.