Interdiffusion and exchange coupling in Cr overlayers on a Fe(001) substrate - art. no. 024413

The influence of interfacial interdiffusion on the magnetic order in ultrat hin epitaxial Cr films on a Fe(001) substrate was studied by means of elect ronic structure calculations. The total coverage of the films was assumed t o be one, two, and six monolayers of Cr while the interdiffusion was simula ted by two-dimensional Cr-Fe alloys in the two atomic layers forming the Cr /Fe interface. Two limiting cases were considered: (i) perfectly ordered al loys, described in terms of a semiempirical tight-binding method using the recursion technique, and (ii) substitutionally disordered alloys, whose ele ctronic structure was determined ab initio using the tight-binding linear m uffin-tin orbital method and the coherent-potential approximation. In both cases, the magnetic coupling of the Cr overlayer to the ferromagnetic Fe su bstrate exhibits similar transitions (pi phase shifts) due to varying compo sitions at the interface. The calculated results provide additional support for recent interpretations of experiments on Fe/Cr/Fe(001) trilayers.