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Infinite coupling magnon theory of quantum Heisenberg magnetic models of spin s

Bang-Gui Liu·Gerd Czycholl
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Abstract

An infinity magnon coupling term is introduced into the Holstein-Primakoff transformed forms of the Heisenberg ferromagnetic and antiferromagnetic models of any spin $s$ to rigorously remove the unphysical magnon states. This term makes the series expansion of the square root of the magnon operators become a finite series of magnon operator products. Under a simple Hubbard-like approximation our infinite coupling theory yields much better result than the existing spin wave theories, especially near transition temperatures.

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Bang-Gui Liu, Gerd Czycholl. 1997-10-24. Infinite coupling magnon theory of quantum Heisenberg magnetic models of spin s. https://arxiv.org/abs/cond-mat/9710261

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