Phase diagrams of a transverse Ising bilayer system

Abstract

Critical properties of a spin- 1 2 transverse Ising bilayer system consisting of two different ferroelectric slabs with a same thickness L are studied on the basis of the two theoretical frameworks of the differential operator technique, namely the effective-field theory and the decoupling approximation, superior to the Bethe–Peierls approximation. We find some unexpected phenomena in the phase diagrams with L=1, such as the reentrant phenomenon (or the reduction to zero of the critical temperature in an abnormal form), due to the competition of the interslab interaction and the transverse field. They can be obtained from both the approximations and seem to be independent of the theoretical approximation.