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The European Physical Journal B
ISSN: 1434-6028 (printed version)
ISSN: 1434-6036 (electronic version)
Abstract Volume 5 Issue 3 (1998) pp 687-695
Mixed spin transverse Ising model with longitudinal random crystal field interactions
N. Benayad (1), R. Zerhouni (1), A. Klümper (2) (a)
(1) Groupe de Mécanique Statistique des Transitions de Phases et Phénomènes Critiques, Laboratoire de Physique Théorique, Université Hassan II, Faculté des Sciences Aîn Chock, BP 5366 Maârif, Casablanca, Morocco
(2) Institut für Theoretische Physik, Universität zu Köln, Zülpicher Strasse 77, 50937 Köln, Germany
Received: 13 February 1998 / Accepted: 17 March 1998
Abstract: The effect of a longitudinal random crystal field interaction on the phase diagrams of the mixed spin transverse Ising model consisting of spin-1/2 and spin-1 is investigated within the finite cluster approximation based on a single-site cluster theory. In order to expand a cluster identity of spin-1, we transform the spin-1 to spin-1/2 representation containing Pauli operators. We derive the state equations applicable to structures with arbitrary coordination number N. The phase diagrams obtained in the case of a honeycomb lattice (N=3) and a simple-cubic lattice (N=6), are qualitatively different and examined in detail. We find that both systems exhibit a variety of interesting features resulting from the fluctuation of the crystal field interactions.
PACS. 05.30.-d Quantum statistical mechanics - 05.50.+q Lattice theory and statistics; Ising problems - 05.70.-a Thermodynamics
(a) email: kluemper@thp.uni-koeln.de
Article in PDF format (450 KB)
Online publication: October 26, 1998
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