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Anisotropic Ashkin‐Teller Model in a Transverse Field
Author(s) -
Bahmad L.,
Benyoussef A.,
EzZahraouy H.
Publication year - 2001
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 - 10.1002/1521-3951(200108)226:2<403::aid-pssb403>3.0.co;2-3
Subject(s) - transverse plane , phase diagram , condensed matter physics , physics , anisotropy , field (mathematics) , transverse field , phase (matter) , spin (aerodynamics) , mean field theory , quantum mechanics , mathematics , thermodynamics , ising model , structural engineering , pure mathematics , engineering
Magnetic properties and phase diagrams of a spin‐1/2 anisotropic Ashkin‐Teller model in a transverse field are studied using the mean field theory. On the one hand, it is found that there exists a critical value of the transverse field Ω c / J 1 above which the partially ordered phase 〈σ S 〉 appears at very low temperature and sufficiently large values of the four‐spin interaction coefficient J 4 / J 1 . Such result is not obtained in the Ω / J 1 = 0 case. On the other hand, the multicritical behaviour is also studied as a function of the transverse field Ω / J 1 for selected values of the spin interaction coefficient J 2 / J 1 . However, depending on the transverse field value, and a fixed J 2 / J 1 value, four varieties of phase diagrams are found. General formulae are established for an arbitrary coordination number q . The phase diagrams and the behaviour of the transverse and longitudinal magnetisations are given for q = 4.