Magnetic properties in ferroelectric superlattices described by a transverse spin-1/2 Ising model

The temperature dependence of the longitudinal magnetization as well as the longitudinal susceptibility of a ferroelectric superlattice described by a transverse spin- Ising model are studied using the effective field theory with a probability distribution technique that accounts for the self-spin correlations. When the slab thicknesses are larger, the temperature dependence of the magnetization shows a steplike structure. The susceptibility becomes infinite at the critical temperature Tc and shows a finite peak corresponding to the rapid decrease in the magnetization near the bulk critical temperature of slab B. The height of the finite peak decreases with the decrease in the slab thicknesses. When they become so thin that the magnetization profiles are predominantly controlled by the interface, the finite peak in the susceptibility as well as the steps in magnetization disappear.