Abstract
The usual Heisenberg Hamiltonian with bilinear exchange -2JS→1•S→2 has been extended to include a biquadratic term -2αJ(S→1•S→2)2, with an adjustable parameter α. A method equivalent to constant coupling was employed to calculate the effect of the biquadratic exchange term on the Curie temperature, magnetization, susceptibility, specific heat, and entropy for lattices with spin-1 atoms. As α goes from 0 to 1, the Curie temperature falls by a factor 2 to 3, while the asymptotic Curie temperature is reduced by the factor 2. The magnetization rises much more rapidly below TC, and the specific heat has a peak and discontinuity several times higher for α=1. The curvature of the inverse susceptibility increases with α, as does the entropy change taking place above TC. © 1971 The American Physical Society.
Recommended Citation
H. A. Brown, "Heisenberg Ferromagnet With Biquadratic Exchange," Physical Review B, vol. 4, no. 1, pp. 115 - 121, American Physical Society, Jan 1971.
The definitive version is available at https://doi.org/10.1103/PhysRevB.4.115
Department(s)
Physics
International Standard Serial Number (ISSN)
0163-1829
Document Type
Article - Journal
Document Version
Final Version
File Type
text
Language(s)
English
Rights
© 2023 American Physical Society, All rights reserved.
Publication Date
01 Jan 1971
