Berlin 2012 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 101: Transport: Nanoelectronics II - Spintronics and Magnetotransport (jointly with TT, MA)
HL 101.4: Vortrag
Freitag, 30. März 2012, 10:15–10:30, BH 243
Magnetic impurities on Bi thin films — •Daniel Lükermann1, Sergii Sologub2, Christoph Tegenkamp1, and Herbert Pfnür1 — 1Leibniz Universität Hannover, Institut für Festkörperphysik, Appelstr. 2, 30167 Hannover — 2Institute of Physics, National Ac. of Sc. Ukraine, Nauky Av. 46, 03028 Kyiv, Ukraine
The semimetal bismuth has attracted a lot of interest because of its unique electronic properties such as a low carrier concentration and a large mobility. Furthermore, the surface states reveal a pronounced Rashba splitting and the conductivity can be well discriminated from bulk contributions if thin films are grown on Si(111) substrates, making surface related effects accessible even in macroscopic conductance measurements.
In order to elucidate the effect of spin-related scattering at impurities, magnetic and non-magnetic metals were adsorbed on thin films of epitaxially grown Bi(111) and investigated by means of conductance and magneto-conductance measurements.
We observe a very strong reduction of conductance by roughly 30 % for adsorbate concentrations of less than 2% of a monolayer both for Bi- and Co-atoms, whereas Fe-atoms only show an effect of 15 %, ruling out the simple assumption of enhanced spin-flip-scattering of the spin-polarized carriers at magnetic impurities.
An evaluation of magneto-conductance and Hall-effect data reveals that the charge transfer from the impurity atoms into the surface states of bismuth plays an important role and can not be neglected in interpreting the data.