Dresden 2014 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 42: Topological insulators (organized by O)
HL 42.4: Talk
Tuesday, April 1, 2014, 11:15–11:30, GER 38
Barrier-free sub-surface incorporation of magnetic impurities into the Bi(111) surface: Manipulation of the protected surface state - Experiment — •C. Klein1, P. Zahl2, N. Vollmers3, U. Gerstmann3, D. Lückermann4, G. Jnawali1, H. Pfnür4, C. Tegenkamp4, W.-G. Schmidt3, P. Sutter2, and M. Horn-von Hoegen1 — 1Faculty of Physics and CENIDE, University of Duisburg-Essen, DE — 2Center for Functional Nanomaterials, Brookhaven National Laboratory, New York, USA — 3Department of Physics, University of Paderborn, DE — 4Institut for Solid State Physics, University of Hannover, DE
Due to the large spin orbit coupling, electron backscattering within the Bi(111) surface states is strongly suppressed. In order to identify possible scattering mechanisms we performed low temperature scanning tunneling microscopy (LT-STM) measurements in which sub-monolayer amounts of 3d-metals (Fe, Co, Ni, Cu) were deposited at 5K. The metal atoms become immediately embedded in a sub-surface site, as they are not present in STM topography. They only become apparent in STS at tunneling conditions close to the Fermi-energy, as they are surrounded by a pronounced anisotropic threefold electronic scattering pattern with lateral dimensions of more than 10 nm. DFT calculations indeed confirm a barrier free incorporation of the 3d-metal impurities into the first Bi-Bilayer even at such low temperatures. This incorporation effect is limited to 3d-metals, as screening effects of the s- and p- orbitals are of great importance and leads to an effective reduction of the free surface energy of about 5 eV.