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Tricritical Behaviour in a Simple Model of an Itinerant Antiferromagnet
Author(s) -
Chamati H.
Publication year - 1994
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.2221820120
Subject(s) - tricritical point , condensed matter physics , antiferromagnetism , phase diagram , plane (geometry) , physics , phase transition , ground state , paramagnetism , coupling constant , simple (philosophy) , phase (matter) , electron , spin (aerodynamics) , thermodynamics , quantum mechanics , mathematics , geometry , epistemology , philosophy
The thermodynamics of a simple electron—spin system describing a paramagnetic—antiferromagnetic phase transition is considered for an arbitrary value of the coupling constant in the presence of doping controlled by the chemical potential μ. The ground state is studied exactly, and a second‐order phase transition with respect to μ is found. The case of nonzero temperature is examined numerically. The Landau expansion depending on two parameters is analyzed near the critical line and in the vicinity of the tricritical point (μ*, T *) in the (μ, T )‐plane. The phase diagram in the ( n , T )‐plane ( n is the electron concentration) shows a coexistence phase for 0 < T ≦ T * and the existence of an isolated point at T = 0.