Critical Point of Ising Films with Different Growth Directions

The critical temperature Tc of a spin-1/2 Ising film of cubic structures is calculated by the variational cumulant expansion method for three directions of growth.The results from different growth directions are analysed and compared with each other.In the present model,the Tc values depend largely on the number of nearest neighbors in a monolayer for films with the same number of monolayers but grown in different directions.For sc,bcc and fee structures,the highest Tc is found along the(100),(110),and(111)direction,respectively.