Cr-Fe surface alloy on Fe substrate: CPA-TB-LMTO and semi-empirical TB calculations

We present results of LSDA electronic structure calculations for the initia l growth stage of epitaxial Cr overlayers on a ferromagnetic Fe(001) substr ate in the presence of interdiffusion at the Cr/Fe interface. The interfaci al interdiffusion is simulated by a two-dimensional substitutionally disord ered alloy and the corresponding self-consistent electronic structure is ob tained within the tight-binding linear muffin-tin orbital (TB-LMTO) method and the coherent-potential approximation (CPA). We analyse the total energi es of different solutions of the LSDA-CPA problem and discuss several topic s relevant to the Cr/Fe system, e.g. segregation tendencies for ultra-thin Cr films and a magnetic pi phase shift for thicker Cr films. A comparison o f the ab initio results to a semiempirical tight-binding theory and experim ent is presented as well.