Dresden 2017 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 47: Superconductivity: Properties and Electronic Structure 2

TT 47.10: Talk

Wednesday, March 22, 2017, 17:45–18:00, HSZ 103

topological quantum phase transition and superconductivity induced by pressure in the bismuth tellurohalide BiTeI — •Yanpeng Qi¹, Wujun Shi^1,2, Pavel G. Naumov¹, Nitesh Kumar¹, Raman Sankar^3,4, Walter Schnelle¹, Chandra Shekhar¹, F. C. Chou⁴, Claudia Felser¹, Binghai Yan^1,2,5, and Sergey A. Medvedev¹ — ¹Max Planck Institute for Chemical Physics of Solids, 01187 Dresden, Germany — ²School of Physical Science and Technology, ShanghaiTech University, Shanghai 200031, China — ³Institute of Physics, Academia Sinica, Taipei 10617, Taiwan. — ⁴Center for Condensed Matter Sciences, National Taiwan University, Taipei 10617, Taiwan. — ⁵Max Planck Institute for the Physics of Complex Systems, 01187 Dresden, Germany.

A pressure-induced topological quantum phase transition has been theoretically predicted for the semiconductor BiTeI with giant Rashba spin splitting. In this work, the evolution of the electrical transport properties in BiTeI and BiTeBr is investigated under high pressure. The pressure-dependent resistivity in a wide temperature range passes through a minimum at around 3 GPa, indicating the predicted transition in BiTeI. Superconductivity is observed in both BiTeI and BiTeBr while the resistivity at higher temperatures still exhibits semiconducting behavior. Theoretical calculations suggest that the superconductivity may develop from the multi-valley semiconductor phase. The superconducting transition temperature Tc increases with applied pressure and reaches a maximum value of 5.2 K at 23.5 GPa for BiTeI (4.8 K at 31.7 GPa for BiTeBr), followed by a slow decrease.