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arXiv · 1606.07960

Observation of Optical and Electrical In-plane Anisotropy in High-mobility Few-layer ZrTe5

Gang Qiu·Yuchen Du·Adam Charnas·Hong Zhou·Shengyu Jin·Zhe Luo·Dmitry Zemlyanov·Xianfan Xu·Gary Cheng·Peide D. Ye
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Abstract

Transition metal pentatelluride ZrTe5 is a versatile material in condensed-matter physics and has been intensively studied since the 1980s. The most fascinating feature of ZrTe5 is that it is a 3D Dirac semimetal which has linear energy dispersion in all three dimensions in momentum space. Structure-wise, ZrTe5 is a layered material held together by weak interlayer van der Waals force. The combination of its unique band structure and 2D atomic structure provides a fertile ground for more potential exotic physical phenomena in ZrTe5 related to 3D Dirac semimentals. However the physical properties of its few-layer form have yet to be thoroughly explored. Here we report strong optical and electrical in-plane anisotropy of mechanically exfoliated few-layer ZrTe5. Raman spectroscopy shows significant intensity change with sample orientations, and the behavior of angle-resolved phonon modes at the gamma point is explained by theoretical calculation. DC conductance measurement indicates a 50% of difference along different in-plane directions. The diminishing of resistivity anomaly in few-layer samples indicates the evolution of band structure with reduced thickness. Low-temperature Hall experiment sheds lights on more intrinsic anisotropic electrical transport, with hole mobility of 3,000 and 1,500 cm2/Vs along a-axis and c-axis respectively. Pronounced quantum oscillations in magneto-resistance are observed at low temperatures with highest electron mobility up to 44,000 cm2/Vs.

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Gang Qiu, Yuchen Du, Adam Charnas, Hong Zhou, Shengyu Jin, Zhe Luo, Dmitry Zemlyanov, Xianfan Xu, Gary Cheng, Peide D. Ye. 2016-06-25. Observation of Optical and Electrical In-plane Anisotropy in High-mobility Few-layer ZrTe5. https://doi.org/10.1021/acs.nanolett.6b02629

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