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O: Fachverband Oberflächenphysik
O 36: Poster Session III: Electronic structure of surfaces: Spectroscopy, surface states I
O 36.6: Poster
Tuesday, March 2, 2021, 10:30–12:30, P
Emergence of unusually high Na2IrO3 surface conductivity prepared in UHV — •Máté Stark1, Thomas Dziuba1, Ina Pietsch2, Philip 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, where both a spin liquid ground state and topologically insulating behaviour are theoretically predicted [1]. In this work, we perform transport measurements of freshly cleaved Na2IrO3 crystals in ultra-high vacuum. Making use of the insulating nature of bulk Na2IrO3 allows us to separate surface-related conductivity of freshly cleaved crystals from bulk transport. We compare the electrical conductivity of the uncleaved and cleaved surface as well as of the surface after degradation in air as a function of temperature between 150 K and 300 K. We find a severe deviation from the usual variable-range-hopping transport [2] and complete domination of the surface conductivity for low temperatures. The freshly cleaved crystal showed a saturation of the sheet resistance at about 2,9 kΩ at low temperatures. After the degradation of the surface in air, the conductivity of the surface decreased, and we measured a general change in the temperature dependence compared to the freshly cleaved surface. Work supported by DFG through SPP 1666 and TRR80. Ref.: [1] Phys. Rev. 108, 106401 (2012), [2] Phys. Rev. B82, 064412 (2010)