Effective critical exponent of the magnetization in ferromagnetic Ising films with amorphous surfaces

The characteristic influence of the exchange interactions and amorphization at the surface on the critical behavior of a ferromagnetic Ising film is examined, by the use of effective field theory with a probability distribution technique that accounts for the self spin correlations. Depending on the ratio of the surface exchange interactions to the bulk ones, R = J(s)/J, and the amorphization delta, many characteristic behaviors are obtained in the magnetic properties, as discussed in the previous work (Physica Scripta 59, 72 (1999)). In particular, the critical effective exponent beta(eff) of the magnetization in the film with a thickness L is studied. We find some new phenomena of beta(eff) depending on the values of L, R, and delta.