Dresden 2020 – scientific programme
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O: Fachverband Oberflächenphysik
O 34: Poster Session - Topological Insulators
O 34.4: Poster
Monday, March 16, 2020, 18:15–20:00, P1C
Macroscopic investigation of conducting Na2IrO3 surfaces prepared in UHV — •Máté Stark1, Thomas Dziuba1, Ina Pietsch2, Philipp Gegenwart2, and Martin Wenderoth1 — 1IV. Physikalisches Institut, Georg-August-Universität Göttingen, Germany — 2Lehrstuhl für Experimentalphysik VI, Zentrum für elektronische Korrelationen und Magnetismus, Universität Augsburg, Germany
Na2IrO3 is a prototypical material in the honeycomb iridate family, which has also been proposed theoretically to exhibit topological protected surface states [1]. Experimental evidences for such surface states are lacking, possibly because of the high reactivity of Na2IrO3 in air, leading to rapid degradation of its surface. To overcome this problem we evaporated gold contacts and cleaved the crystal in UHV. We studied the electrical conductivity of the uncleaved and cleaved surface as well as of the surface after degradation in air as function of temperature between 100 K and 300 K, and compared the results with the conductivity of the bulk. The freshly cleaved crystal showed in contrast to the previously reported semiconductor-like behaviour a saturation of the sheet resistance at about 2,9 kΩ at low temperatures [2]. After the degradation of the surface in air, the conductivity of the surface decreased at low temperatures, and we measured a general change in the temperature dependence compared with the freshly cleaved surface. Conclusively we report a conducting surface on the freshly cleaved Na2IrO3 surface. References: [1] Phys. Rev. 108, 106401 (2012), [2] Phys. Rev. B82, 064412 (2010)