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On the Fluctuations and Phase Transitions in Dicke‐Like Models
Author(s) -
Loos J.
Publication year - 1984
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.2221230223
Subject(s) - spins , hamiltonian (control theory) , physics , phase transition , statistical physics , quantum mechanics , classical mechanics , condensed matter physics , mathematics , mathematical optimization
The fluctuation theory based on the functional integration method is developed for a multimode Dicke‐Hamiltonian with arbitrary spins and with antiresonant terms included. The effective classical Hamiltonian of the fluctuations is deduced and the equilibrium phase transition, the existence of soft modes as well as the general equations of state are discussed in this unified approach. The consequences of the rotating‐wave approximation are clearly distinguished. The solid state phenomena of the cooperative Jahn‐Teller effect and of spin‐reorientation are implied in these considerations.