Prog. Theor. Phys. Supplement No.80 (1984) pp. 146-155

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Specific Heat of a Quantum Spin Chain of an Easy-Plane Type under an In-Plane Magnetic Field

— Ferromagnetic Chain with S = 1 —

Toshio Tsuzuki

Department of Physics, Tohoku University, Sendai 980

(Received September 29, 1984)

Abstract:

Quantum statistical mechanics is developed for an easy-plane ferromagnetic chain under an in-plane magnetic field. A pair product approximation is made for the density matrix. A transfer integral expression for the partition function is formulated by the use of the coherent state of spin.
Specific heat is computed as a function of temperature and magnetic field for the case of strong single-ion anisotropy. From our qualitative study it is suggested that, beyond the sine-Gordon approximation, simultaneous consideration of the quantum effect and the instability against the off-plane fluctuation (the Kumar-Magyari-Thomas instability) is necessary to explain specific heat, in particular, and thermodynamic quantities, in general, of the present system.

URL : http://ptp.ipap.jp/link?PTPS/80/146/
DOI : 10.1143/PTPS.80.146

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Citing Article(s) :

Progress of Theoretical Physics Vol. 73 No. 6 (1985) pp. 1352-1368 :
An Improved Transfer Matrix Method for Quantum Spin Systems

Toshio Tsuzuki
Progress of Theoretical Physics Supplement No.94 (1988) pp. 73-114 :
Statistical Mechanics of Soliton Systems

Toshio Tsuzuki and Kazuo Sasaki