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Self‐Consistent Dynamical Theory for Heisenberg Spin Glasses
Author(s) -
Schreiber J.,
Schulz D.
Publication year - 1985
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.2221270113
Subject(s) - spin glass , physics , spin (aerodynamics) , heisenberg model , condensed matter physics , quantum fluctuation , quantum , order (exchange) , specific heat , quantum mechanics , thermodynamics , ferromagnetism , finance , economics
A sel‐consistent RPA theory is constructed to describe a spin glass (SG) state in the Heisenberg model ( S = 1/2). The investigations are based on the assumption of a collinear spin structure and of strong quantum fluctuations: 〈 S i z 〉 ≪ 1/2 (quantum spin glass QSG). In the lowest order the structural fluctuations are expressed by the fluctuations of the molecular fields H i , for which the probability distribution is self‐consistently determined by a Lorentzian one with a temperature dependent width Γ( T ). This quantity plays the role of an order parameter. The temperature dependence of the specific heat and the susceptibility qualitatively agree with experiments.