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On the relation between structural phase transitions and spin reorientation transition in anisotropic ferromagnets
Author(s) -
Schreiber J.,
Bläsing J.,
Flach S.
Publication year - 1989
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.2221520134
Subject(s) - condensed matter physics , ferromagnetism , anisotropy , phase transition , hamiltonian (control theory) , physics , soft modes , spin crossover , quantum phase transition , scalar (mathematics) , lattice (music) , crossover , quantum mechanics , mathematics , geometry , artificial intelligence , computer science , acoustics , dielectric , ferroelectricity , mathematical optimization
On the basis of Hollstein‐Primakoff transformation for the Heisenberg model with anisotropy a new theoretical description of the spin reorientation transition in ferromagnetic systems is given. An effective Hamiltonian is derived, which is identical with the scalar Φ 4 ‐lattice model of structural phase transitions. Especially the appearance of precursor clusters of the low temperature phase above the phase transition point is discussed. If the reorientation transition takes place at sufficiently low temperatures the existence of defect pinned cluster states can lead to glass‐like behaviour. Experimental consequences are considered. In relation to the anomalous properties of high‐ T c superconductors special attention is paid to the importance of a crossover from a soft mode or mean‐field‐like behaviour into the regime of cluster fluctuations in strongly non‐linear dynamical systems.