Interplay of structure and magnetism in surfactant-assisted grown metastable Fex Cu1-x alloy films.

NIÑO, M.A.; CAMARERO, J.; MIKUSZEIT, N.; DE MIGUEL, J.J.; MIRANDA, R.; GÓMEZ, L.; FERRÓN, J.; ABRUJAN, R.; FUKUMOTO, K.; KUCH, W.; WANG, S.G.; TREG, C.; KIRSCHNER, J.

Paris, Francia

Conferencia; 24th European Conference on Surface Science; 2006

Artificial Fe-Cu alloy films are prepared in-situ at room temperature on a Cu(111) substrate by thermal coevaporation, using a Pb layer as surfactant to reduce the film roughness and the atomic mobility, thus preventing the segregation of the two components. These random alloy films retain the fcc structure for several nanometers of thickness, depending on the Fe concentration up to a maximum of 70%. The fcc-to-bcc transition can be controlled using Fe concentration and temperature as parameters. The growth process has been analysed with the help of Monte Carlo simulations in continuous space, describing the atomic interaction by means of realistic empirical potentials. The magnetic characteristicis of these metastable alloy films have been studied by means of Magneto Optic Kerr Effect and X-ray Magnetic Circular Dichroism measurements. These experiments reveal the presence of a buried layer of paramagnetic alloy that remains fcc at room temperature even after the upper layers have turned ferromagnetic and bcc.