CHINESE JOURNAL OF PHYSICS VOL. 38, NO. 6 DECEMBER 2000

The Phase Transitions in Ferroelectric Films Described by
a Transverse Spin-1/2 Ising Model

A. Saber, A. Ainane and M. Saber

Département de Physique, Faculté des Sciences

Université Moulay Ismail, B.P. 4010, Meknès, Marocco

and

Departamento de Física, Universidad Carlos III de Madrid

28911 Leganès, Madrid, Spain
(Received May 23, 2000)

The critical temperature in ferroelectric films described by a transverse spin-1/2 Ising model is studied using effective field theory along with a probability distribution technique. We discuss an L layer film of simple cubic symmetry with nearest-neighbor interactions in which the strengths of the interactions are different from the bulk values in the surface layers. We derive the phase diagram, the magnetization profiles and the susceptibilities. In such films, the critical temperature can shift to either a lower or higher temperature compared with the corresponding bulk value. The film longitudinal susceptibility diverges at the film critical temperature.

PACS. 75.70.-i $\,\,$- Magnetic films and multilayers.
PACS. 75.70.Ak - Magnetic properties of monolayers and thin films.
PACS. 75.70.Cn - Interfacial magnetic properties.

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