Regensburg 2019 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 88: Electronic Structure of Surfaces II
O 88.7: Vortrag
Donnerstag, 4. April 2019, 16:30–16:45, H26
Electronic structure of the LaB6 (001)-surface — •Florian Sohn1,2, Philipp Buchsteiner3, Jan Voigt3, Martin Wenderoth3, and Peter E. Blöchl1,2 — 1Institut für theoretische Physik, Technische Universität Clausthal — 2Institut für theoretische Physik, Universität Göttingen — 3IV. Physikalisches Institut, Universität Göttingen
Lanthanum hexaboride (LaB6) is the first compound among the rare earth hexaborides. Due to its low work function and high melting point, LaB6 is widely used for thermionic electron emission. Recently, the LaB6 (001)-cleavage plane has been investigated with scanning tunneling microscopy (STM) and spectroscopy (STS). Our data shows a mainly 2×1 reconstructed surface. We rationalize the constant current topographies and differential conductance spectra by simulations based on density functional theory (DFT). Our simulations of a LaB6 (001)-surface, terminated by chains of lanthanum ions, show, that in STM measurements with positive bias voltage the d-orbitals of the topmost lanthanum ions are addressed. In contrast, at small negative bias voltages, a broad feature in the local density of states below the Fermi energy could be successfully resolved by both STS and DFT and is traced back to surface boron orbitals. Our study shows the necessity of surface calculations in order to understand the experimental data in detail and can be applied to various model systems.