Manipulating Magnetic Anisotropy In Metallic Multilayers And Studies On Atomic-scale Dynamics

The magnetic anisotropy of nanoscale structures, being one of the key parameters in spintronics, has recently received considerable attention from both experiments and theoretical perspectives. The strain effect on magnetic properties of metallic multilayers has been investigated systematically with ab initio method. By choosing Fe-Ir multilayers as a model system, we demonstrated that the magnetic anisotropy(MA) can be tuned at a large range by the strain. Moreover, microscopic mechanism of the MA’s dependence on components and structures is revealed. Furthermore, by replacing the interspaced nonmagnetic Ir layers in Fe-Ir systems with Pt, we get Fe-Pt multilayers. As Pt has a different band filling with that of Ir, both the magnitude of MA and the easy axis of Fe-Pt systems can be manipulated by the strain. The origin of the MA’s dependence on strain is revealed by analyzing electronic structures of the selected systems.In addition, studies on atomic-scale dynamics have been performed with Nudged Elastic Band Method(NEB)based on ab initio. It turns out that the energy barrier from hcp site to fcc site for a Cu atom residing on a single-crystal Cu(111) surface decreases as an STM tip approaching, For a Co atom residing on Cu(111) surface, a similar trend is observed as an STM tip approaching, while the barrier changes more quickly. This is because that the interaction between Cu and Co is stronger than that between Cu and Cu as the STM tip is made up with Cu atoms. This trend can be generalized to a Co atom on Cu(100) surface. The barrier’s decreasing is caused by the relaxation of the atoms in the substrate as an STM tip’s approaching.