Temperature-driven topological phase transition and intermediate Dirac semimetal phase in ${\mathrm{ZrTe}}_{5}$
Xu, BingDepartment of Physics and Fribourg Center for Nanomaterials, University of Fribourg, Switzerland
Zhao, L. X.Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, China
Marsik, PremyslDepartment of Physics and Fribourg Center for Nanomaterials, University of Fribourg, Switzerland
Sheveleva, EvgeniiaDepartment of Physics and Fribourg Center for Nanomaterials, University of Fribourg, Switzerland
Lyzwa, FryderykDepartment of Physics and Fribourg Center for Nanomaterials, University of Fribourg, Switzerland
Dai, Y. M.Center for Superconducting Physics and Materials, National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, China
Chen, G. F.Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, China
Qiu, X. G.Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, China
Bernhard, ChristianDepartment of Physics and Fribourg Center for Nanomaterials, University of Fribourg, Switzerland
English
We present an infrared spectroscopy study of ZrTe5, which confirms a recent theoretical proposal that this material exhibits a temperature-driven topological quantum phase transition from a weak to a strong topological insulating state with an intermediate Dirac semimetal state around Tp ≃ 138 K. Our study details the temperature evolution of the energy gap in the bulk electronic structure. We found that the energy gap closes around Tp, where the optical response exhibits characteristic signatures of a Dirac semimetal state, i.e., a linear frequency-dependent optical conductivity extrapolating to the origin (after subtracting a weak Drude response). This finding allows us to reconcile previous diverging reports about the topological nature of ZrTe5 in terms of a variation of Tp that depends on the crystal growth condition.