Berlin 2018 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 51: Poster: Electronic Structure of Surfaces: Spectroscopy, Surface States
O 51.16: Poster
Dienstag, 13. März 2018, 18:15–20:30, Poster B
Investigation of Honeycomb-Iridate Surfaces by Means of STM and STS — •Thomas Dziuba1, Felix Lüpke1, Friedrich Freund2, Soham Manni2, Philipp Gegenwart2, and Martin Wenderoth1 — 1IV. Physikalisches Institut, Georg-August-Universität Göttingen, Germany — 2Experimentalphysik VI, Universität Augsburg, Germany
Honeycomb iridates A2IrO3 (A=Na or Li) have attracted much interest as prototype spin-orbit Mott insulators with magnetic Kitaev exchange interaction. They are also considered as promising candidates for novel correlated topological insulator behavior. This motivates detailed microscopic investigations of the surface properties by scanning tunneling microscopy (STM) and spectroscopy (STS). Honeycomb iridates consist of an alternating stacking of negatively charged honeycomb iridate structures and positively charged hexagonal alkali metal layers [1]. Optical conductivity indicates a large bulk bandgap (340 meV [2]). We found, that the surface of both, pure and partly Li-doped sodium iridate shows 1 × 1- and 3 × 1 reconstructions, that in all cases exhibit a surface band gap. This gap depends crucially on the particular reconstruction as well as on the alkali metal configuration, with higher Li-content leading to smaller bandgaps [1]. Recently, α-Li2IrO3 single crystals were synthesized [3]. We report first STM/STS measurements on them, revealing interesting surface properties. Work supported by DFG SPP1666. [1] F. Lüpke et al, Phys. Rev. B 91, 041405(R) (2015) [2] V. Hermann et al, Phys. Rev. B 96, 195137 (2017) [3] F. Freund et al, Sci. Rep. 6, 35362 (2016)