Critical Point of Magnetic Nanostructures in the Ising Model

Abstract

The critical temperature T-c of magnetic nanostructures is calculated by the variational cumulant expansion in the Ising model. Structures of column, plate and cubic shapes are constructed for the study of shape effects. It is found that T-c increases with the decreasing surface to volume ratio. The dependence of T-c on the growth direction is also studied for various cubic lattices.