Berlin 2015 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 92: Topological Insulators I (jointly with MA, DS, HL, O)
TT 92.9: Talk
Thursday, March 19, 2015, 11:30–11:45, EB 202
Atomic structure and magnetism of Fe on Bi2Se3 — •Andrey Polyakov1, Holger L. Meyerheim1, E. Daryl Crozier2, Robert A. Gordon3, Maia G. Vergniory4, Arthur Ernst1, Evgueni V. Chulkov4, and Jürgen Kirschner1,5 — 1MPI f. Mikrostrukturphysik, D-06120 Halle, Germany — 2SFU, Burnaby, V5A 1S6 BC, Canada — 3CLS at APS Sector 20, Argonne, IL, USA — 4DIPC, San Sebastian, Spain — 5MLU Halle-Wittenberg, Germany
We have carried out extended x-ray absorption fine structure (EXAFS) and surface x-ray diffraction (SXRD) experiments in combination with ab-initio calculations to investigate the geometric and magnetic properties of iron deposited on the (0001) surface of the topological insulator Bi2Se3 in the coverage range between about 0.2 and 1.5 monolayers (ML). For iron deposited at T=170 K in the low coverage limit no polarization dependence of the EXAFS amplitude (electric field vector parallel vs. perpendicular to the surface of the bulk crystal) could be observed. In combination with the nearest neighbor distance of 2.42 Å this suggests that Fe atoms substitute bismuth atoms involving a local relaxation of the neighboring selenium atoms. Ab-initio calculations support this structural model and predict antiferromagnetic ordering of iron [1]. SXRD data collected at 1.5 ML indicate that iron atoms also occupy threefold hollow surface sites. Mild annealing leads to the formation of a bulk FeSe like structure. [1] M. G. Vergniory et al. PRB 89, 165202 (2014); This work is supported by SPP 1666 (Topological Insulators). Work at APS sector 20 is supported by the CLS and by US DOE under Contract No. DE-AC02-06CH11357