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Cumulant expansion for systems with large spins

K. Kladko·P. Fulde·D. A. Garanin
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Abstract

A method is proposed for obtaining a systematic expansion of thermodynamic functions of spin systems with large spin S in powers of 1/S. It uses the cumulant technique and a coherent-state representation of the partition function Z. The expansion of Z in terms of cumulants yields an effective classical Hamiltonian with temperature-dependent quantum corrections. For the Heisenberg quantum Hamiltonian, they have a non-Heisenberg form. The effective Hamiltonian can be solved by methods familiar for classical systems.

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BibTeXRIS

K. Kladko, P. Fulde, D. A. Garanin. 2000-02-29. Cumulant expansion for systems with large spins. https://doi.org/10.1209/epl%2Fi1999-00104-y

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