Keywords: 
• 铁电薄膜 /
• 横场伊辛模型 /
• 相图 /
• 居里温度

Abstract: Within the framework of effective-field theory with correlations, phase transition properties of ferroelectric thin films with differ-ent symmetrical surfaces described by the spin-1/2 transverse field Ising model are studied systematically by the differential operator technique. According to the coupling equations with the layer polarization average, the analytical general equations for phase dia-grams of multiple-surface ferroelectric thin films with different surface layers have been derived. Then, effects of various parameter modifications on the crossover values from the FPD (ferroelectric-dominant phase diagram) to the PPD (paraelectric-dominant phase diagram) and phase transition regions in the parameter space are discussed in detail. In comparison with the mean-field approximation, the results indicate that the effective-field theory with correlations maybe reduce the ferroelectricity of the ferroelectric thin films more exaggeratedly than the mean-field approximation to some extent.