Dresden 2014 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 2: Magnetic Clusters

MA 2.5: Vortrag

Montag, 31. März 2014, 10:30–10:45, HSZ 401

Magnetism of sp-impurity-decorated grain boundaries and surfaces — Monika Vsianska^1,2,3, Hana Vemolova³, and •Mojmir Sob^1,2,3 — ¹Central European Institute of Technology, CEITEC MU, Masaryk University, Brno, Czech Republic — ²Institute of Physics of Materials, Academy of Sciences of the Czech Republic, Brno, Czech Republic — ³Department of Chemistry, Faculty of Science, Masaryk University, Brno, Czech Republic

We present a systematic ab initio study of segregation of 12 non-magnetic sp-impurities (Al, Si, P, S, Ga, Ge, As, Se, In, Sn, Sb and Te) at Σ5(210) grain boundary (GB) and (210) free surface (FS) in fcc ferromagnetic cobalt and nickel and analyze their effect on structure, magnetic and mechanical properties. We determine preferred segregation sites at the Σ5(210) GB for the sp-impurities studied, their segregation enthalpies and strengthening/embrittling energies. In nickel, most of the above impurities nearly kill or substantially reduce the magnetic moments at the FS and, when segregating interstitially (i.e. Si, P, S, Ge, As, Se), also at the GB so that they provide atomically thin magnetically dead layers which may be very desirable in spintronics. Reduction of magnetic moments at the Σ5(210) GB in fcc ferromagnetic cobalt is, in absolute values, very similar to that in nickel. However, as the magnetic moment in bulk cobalt is higher, we do not observe magnetically dead layers here. It turns out that by focused impurity segregation we can generate atomically thin magnetic layers with tailored magnetization, which can contribute to a new development of technologically important materials.