Phase Transitions in a Spin‐1/2 Ising Model of Alternating Magnetic Superlattice

Abstract

Within the framework of the effective field theory, we examine the phase transitions in a spin-1/2 Ising model of an alternating magnetic superlattice. We calculate the critical temperature of the alternating superlattice as a function of the intralayer and interlayer exchange interactions and the film thickness. The effects of modified surface layers on the critical temperature are also considered.

Phase transition properties of a ferroelectric spin-1/2 Ising superlattice

“…Similarly, the four paraelectric planes consist of three planes with bulk paraelectric properties together with one interface plane. This model is different from the one used in the previous calculations [24,[26][27][28][29], which did not assume a separate interface plane between the two media. The existence of interface planes is intrinsic for perovskite ferroelectric superlattices [14].…”

“…Under the mean-field approximation, the dielectric properties of the same system have been studied [20][21][22]. The ferroelectric superlattice described by the Ising model in a transverse field has been studied recently using the effective-field theory [23][24][25][26][27][28][29].…”

The Transverse Ferromagnet Spin–½ Ising Model of an Alternating Magnetic Superlattice

“…In this case, for the calculations we follow Ref. [22]. The only change required here is the replacement of the function tanh (u) by the function…”

“…The critical temperatures were obtained as functions of the thickness of the superlattice with various couplings strengths between nearest neighbor spins in the same material and across the interface. Sy and Ow [19] and Sy [20], using the mean Ðeld approximation, and Saber et al [22], using the e †ective Ðeld theory with a probability distribution technique [24], investigated alternating magnetic superlattices. The critical temperatures were calculated as a function of the thickness of the superlattice for various couplings strengths.…”

“…This model has been used to study various systems [26È32]. Recently the authors of this paper have studied the phase transitions in a Ising model of alternating magnetic spinÈ1 2 superlattice [22], using the e †ective Ðeld theory with a probability distribution technique [24].…”