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Short‐Range Order and Magnetic Properties in Amorphous Heisenberg Ferromagnets
Author(s) -
Maksymowicz A. Z.
Publication year - 1984
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.2221220216
Subject(s) - condensed matter physics , ferromagnetism , magnetism , curie temperature , spin (aerodynamics) , physics , order (exchange) , curvature , ising model , amorphous solid , chemistry , mathematics , crystallography , thermodynamics , finance , economics , geometry
Amorphous A c B 1− c alloys of magnetic A‐and non‐magnetic B‐atoms are considered. Effects of atomic short‐range order, difference 〈Z A 〉 – 〈Z B 〉 of the average coordination numbers, and fluctuations of Z A are discussed. Fluctuations in the exchange integral are not taken into account. Calculations based of the Bethe‐Peierls‐Weiss mean‐field model are compared with results for the Ising model, S = 1/2, with spin‐spin correlations included. As expected, the critical concentration for the onset of magnetism is increased while the Curie temperature and susceptibility are decreased due to magnetic correlations. The same, yet much stronger tendency is induced by the atomic short‐range order favouring A‐B pairs or by fluctuations of Z A when the effect is rather weak. Opposite tendency is observed when 〈Z B 〉 < 〈Z A 〉. Deviations from the Curie‐Weiss law lead to an upward curvature of 1/ X against T , yet the effect is too small to explain a strong upward curvature as observed in experiment, especially near T C .