THE PD-POLARIZATION AT THE PD/FE INTERFACE

The electronic and magnetic properties of the ground state (T = 0 K) at the Pd/Fe(001) interface were investigated through the mean-field parameterized tight-binding method. Structurally, the Pd overlayers occupy the fcc sites of the substrate, with a few percent expansion of the Pd-Pd distances as compared to the bulk fcc Pd. We report results concerning deposition of n Pd layers on semi-infinite Fe. Ferromagnetic polarization of the Pd(n) layers are obtained up to n = 3. For n = 4, we have obtained ferromagnetic polarization of the nearest neighbour Pd overlayer but negative polarization for the three other planes. For n = 5, all the Pd atoms are polarized ferromagnetically unless the surface which has a quasi-zero magnetic moment. In the case of sandwiches Fe(m)/Pd(n)/Fe(m) or superlattices (Fe(m)Pd(n))p we investigate both ferromagnetic and antiferromagnetic couplings between Fe films through the Pd spacer. For completeness we perform also total energy calculations in order to study the exchange coupling displayed by Celinski and Heinrich [J. Magn. Magn. Mater. 99 (1991) L25]. Similar trends are found: ferromagnetic coupling is shown to be stable until n = 5 for Fe5/Pd(n)/Fe5 sandwiches; antiferromagnetic coupling is however stable for n = 6. We discuss the importance of the interface roughness on this oscillation.