Regensburg 2019 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe

O: Fachverband Oberflächenphysik

O 43: Poster Tuesday: Electronic Structure

O 43.9: Poster

Dienstag, 2. April 2019, 18:00–20:00, Poster D

Evidence for Conducting Na₂IrO₃ Surfaces prepared in UHV — •Sarah Maamar¹, Thomas Dziuba¹, Ina Pietsch², Philipp Gegenwart², and Martin Wenderoth¹ — ¹IV. Physikalisches Institut, Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany — ²Lehrstuhl für Experimentalphysik VI, Universität Augsburg, Germany

Honeycomb iridate Na₂IrO₃ attracts considerable interest as prototype material for the study of the Kitaev interaction [1]. However, first-principles-derived tight-binding model calculations have also proposed topologically nontrivial electronic behaviour in this system, namely 2D Quantum Spin Hall [2] or 3D correlated topological insulator [3] states. Experimental evidence for this is still missing, possibly because of the high reactivity of Na₂IrO₃, leading to rapid degradation of its surface. To overcome this problem, we cleave single crystals in ultra-high vacuum (UHV), evaporate gold contacts and study the electrical conductivity as function of temperature between 100 K and 260 K without breaking the UHV conditions. Linear I-V curves prove ohmic contacts. In contrast to previous resistivity measurements, which displayed insulating behaviour [4], our data indicate a saturation of the resistance at low temperature, i.e. a finite conductivity at 100 K. This work is supported by the DFG through the SPP 1666 (Topological Insulators).

[1] S.M. Winter et al., J. Phys.: Condens. Matter 29, 493002 (2017).

[2] A. Shitade et al., Phys. Rev. Lett. 102, 256403 (2009).

[3] C.H. Kim et al., Phys. Rev. Lett. 108, 106401 (2012).

[4] Y. Singh and P. Gegenwart, Phys. Rev. B 82, 064412 (2010).