Phase diagrams of a transverse Ising superlattice based on two theoretical frameworks

The phase diagrams of a superlattice composed from two different alternating ferroelectric slabs with the same thickness L are discussed on the basis of the spin-1/2 transverse Ising model. The two theoretical frameworks of the differential operator technique are applied to the investigations, namely the Zernike approximation and the decoupling approximation superior to the Bethe–Peierls approximation. The unexpected phenomena obtained in the system with L=2, such as the reentrant phenomenon due to the competition of the interslab coupling and the transverse field, can be found by the use of both approximations. They seem to be independent of the theoretical approximation.