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Study of Surface Effects in Quantum Heisenberg and XY Antiferromagnets
Author(s) -
Cabral Neto J.,
Ricardo de Sousa J.
Publication year - 1999
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/(sici)1521-3951(199904)212:2<343::aid-pssb343>3.0.co;2-z
Subject(s) - condensed matter physics , antiferromagnetism , heisenberg model , paramagnetism , ferromagnetism , physics , quantum , anisotropy , quantum fluctuation , classical xy model , quantum phase transition , spin (aerodynamics) , phase transition , quantum mechanics , thermodynamics
Using a finite‐cluster mean‐field approximation, we study the characteristics of phase transitions for the semi‐infinite simple cubic quantum spin‐1/2 anisotropic Heisenberg model with ferromagnetic and antiferromagnetic interactions. The dependence of the critical temperature on the parameter Δ is obtained, where Δ = J s / J b – 1, J s and J b are the nearest‐neighbour coupling constants at the surface and bulk, respectively. Particular attention has been drawn to the difference between the criticality for the F (ferromagnetic) and AF (antiferromagnetic) models. It is shown that quantum influence modifies the criticality of the anisotropic Heisenberg model with T c (F case) < T N (AF case) and T c > T N in the bulk‐paramagnetic and surface paramagnetic critical lines, respectively. On the other hand, the quantum XY model presents the same criticality for the two types of interactions (F and AF).