Engineering the magnetic anisotropy of an ultrathin Co layer sandwiched between films of Mo or Au

Magnetic properties of an ultrathin Co layer deposited on the Mo(1 1 0) or Au(1 1 1) buffers crucially depend on magnetic layer thickness and a cap layer type (Au or Mo, studied in this work). Depending on the sandwich configuration, magnetization is oriented in a perpendicular direction to the plane in the range of smaller Co layer thickness (below 2 nm) or in the sample plane for a thicker layer (3 nm). Moreover, a well-developed two-fold in-plane magnetic anisotropy occurs in the Co layer deposited on the Mo buffer. These features are correlated with crystalline structure studied with the use of numerous complementary methods: reflection high-energy electron diffraction, x-ray diffraction, x-ray reflectivity, nuclear magnetic resonance, and element-sensitive synchrotron techniques, i.e. x-ray linear dichroism and x-ray absorption near edge spectroscopy. Magnetic behaviour, exhibiting volume and surface contributions, is thoroughly discussed in terms of the buffer and cap layer type, thickness-dependent crystalline structure of the Co layer, and the interface quality. (paper)