Structural, electronic, magnetic and spin dependent transport properties of Fe/CaS/Fe (001) heterostructures

Structural, electronic, and magnetic properties of Fe/CaS (001) interfaces and Fe/CaS/Fe (001) heterostructures have been studied by means of a self-consistent Green's function technique for surface and interfaces implemented within the tight-binding linear muffin-tin orbital formalism. Spin dependent transport properties of the Fe/CaS/Fe (001) tunnel junctions with thin and intermediate barriers, in the current-perpendicular-to-plane geometry, have been determined by means of Kubo-Landauer approach implemented within the tight-binding linear muffin-tin orbital formalism. A small charge rearrangement is evidenced at the Fe/CaS (001) interfaces. The iron interfacial magnetic moments are enhanced over the bulk value. A small exchange coupling with the sign depending on the Fe/CaS (001) interface geometric structure and the strength decaying exponentially with the barrier is evidenced. Interfacial charge transfer, interface iron magnetic moments, and tunneling currents are sensitive to the interfacial structure. Interface resonant states have a decisive role in the tunneling process and the main contribution to the current in the ferromagnetic state of the junction is given by the minority-spin electrons. (C) 2013 American Institute of Physics. [http://dx.doi.org/10.1063/1.4790574]