A classical effective Hamiltonian for the quantum easy-plane ferromagnetic chain with an in-plane applied field is introduced by means of a path-integral variational method. It then becomes possible to include quantum effects of the out-of-plane fluctuations in an easily valuable phase-space integral which approximates the quantum partition function. A comparison with experimental data for the excess specific heat of CsNiF3 shows much improvement in the description of this system. In addition, new light is shed on the old problem of defining the classical counterpart of a spin Hamiltonian.

QUANTUM THERMODYNAMICS OF EASY-PLANE FERROMAGNETIC CHAINS / A. CUCCOLI; V. TOGNETTI; P. VERRUCCHI; R. VAIA. - In: PHYSICAL REVIEW. B, CONDENSED MATTER. - ISSN 0163-1829. - STAMPA. - 44:(1991), pp. 903-905. [10.1103/PhysRevB.44.903]

QUANTUM THERMODYNAMICS OF EASY-PLANE FERROMAGNETIC CHAINS

CUCCOLI, ALESSANDRO;TOGNETTI, VALERIO;
1991

Abstract

A classical effective Hamiltonian for the quantum easy-plane ferromagnetic chain with an in-plane applied field is introduced by means of a path-integral variational method. It then becomes possible to include quantum effects of the out-of-plane fluctuations in an easily valuable phase-space integral which approximates the quantum partition function. A comparison with experimental data for the excess specific heat of CsNiF3 shows much improvement in the description of this system. In addition, new light is shed on the old problem of defining the classical counterpart of a spin Hamiltonian.
44
903
905
A. CUCCOLI; V. TOGNETTI; P. VERRUCCHI; R. VAIA
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2158/355076
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