The intermixing induced perpendicular magnetic anisotropy in ultrathin Co/Pt multilayers

Abstract

It has been observed that a perpendicular interface contribution to the magnetic anisotropy can rotate the easy magnetization direction from within the film plane to perpendicular to the film plane when the Co thickness in Co/Pt multilayers is below a critical value that is in the range of (sub) nanometers. In this work, mixed CoPt phases mainly consisting of disordered fcc CoPt were found to be responsible for the perpendicular magnetic anisotropy (PMA) for the film deposition end-Hall voltage equal to 140 V. Estimates of mechanisms that could be responsible for the PMA such as "orange peel" coupling, exchange bias, and magnetostriction indicate that they are too weak. We believe that this PMA is driven by the heat of mixing and relatively higher interfacial energy since the Co layer thickness is about 1 nm. (C) 2009 American Institute of Physics. [DOI: 10.1063/1.3070639]