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Noncritical fluctuations and the temperature dependence of the order parameter
Author(s) -
Franck S.,
Kühnei A.,
Nattermann T.,
Wendt S.
Publication year - 1976
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.2220770225
Subject(s) - quartic function , anharmonicity , tricritical point , condensed matter physics , hamiltonian (control theory) , phase transition , ferroelectricity , first order , physics , perturbation (astronomy) , curie temperature , thermodynamics , quantum mechanics , mathematics , phase (matter) , ferromagnetism , phase diagram , mathematical optimization , dielectric , pure mathematics
An effective Hamiltonian with anharmonic terms of fourth and sixth order is investigated by means of perturbation theory. Noncritical fluctuations of the order parameter lead to a temperature dependence of the coefficient of the quartic term. It turns out that this coefficient can vanish at a certain temperature T 1 . Depending on the parameter of the substance a first‐order phase transition, a tricritical point, or a second‐order phase transition may appear. The model describes the situation in ferroelectric TSCC.