Phase transitions in tetrahedral Ising lattices

After a review of the Renormalization CJroup theory, the phase diagram of unisotro])ic tetrahedral Ising lattice is explored l)y the motivation gained through the recent experimental findings about SiGe alloys. Renormalization Group approcich and the mean-field R(J approximation previously pro])osed by Kinzel ¿ire used. Four different ordered pluises are olxserved. The critical expoiKMit // is Ciih’uhited using the liiUNirized t.ra.nsform<ition ¿iround the fixed points and ('om|)fii’ed with previous works. It is ('oiu'luded tluit the newly observed orderings in Si(!e superlattices are induced by surface effects.