Berlin 2015 – scientific programme
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O: Fachverband Oberflächenphysik
O 2: Surface Magnetism and Spin Phenomena
O 2.4: Talk
Monday, March 16, 2015, 11:30–11:45, MA 004
Magnetotransport at surfaces of epitaxially grown Bi and BiSb thin films — •Philipp Kröger1, Julian Koch1, Sergii Sologub2, Herbert Pfnür1, and Christoph Tegenkamp1 — 1Leibniz Universität Hannover, Festkörperphysik, 30167 Hannover — 2Inst. of Physics, Nat. Acad. of Sc., Nauky Av. 46, 03028 Kyiv, Ukraine
Bi has unique electronic properties such as low carrier concentrations, large mobilities and pronounced Rashba splitting of the surface states. We investigated the manipulation of spin-polarized transport properties in Bi(111) films by controlled adsorption of magnetic adatoms (Fe,Co,Tb,Cr). Besides pronounced effects of charge carrier doping and surface diffusion the spin-orbit scattering rate (1/τSO) can be tuned by the amount and type of the adsorbate giving rise to weak anti-/ weak- localization transitions. To enhance the spin polarization, Bi1−xSbx alloys were grown which exhibit a topological non-trivial phase for certain concentrations x. Magnetotransport measurements of a 30 BL Bi0.82Sb0.18 film on Si(111) reveals weak anti localization behavior. Compared to Bi(111) films the τSO is increased by one order of magnitude reflecting the strong spin-orbit coupling in this system with carrier concentrations of n=1· 1013cm−2 and p=2· 1013cm−2. The corresponding mobilities amounts to µn=260 cm2(Vs)−1 and µp=190 cm2(Vs)−1. By adsorption of Cr (4,8 µB) we got a first insight into the spin dependent scattering processes in this class of material.