Observation of Optical and Electrical In-Plane Anisotropy in High-Mobility Few-Layer ZrTe5

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• 作者：Gang Qiu ; Yuchen Du ; Adam Charnas ; Hong Zhou ; Shengyu Jin ; Zhe Luo ; Dmitry Y. Zemlyanov ; Xianfan Xu ; Gary J. Cheng ; Peide D. Ye
• 刊名：Nano Letters
• 出版年：2016
• 出版时间：December 14, 2016
• 年：2016
• 卷：16
• 期：12
• 页码：7364-7369
• 全文大小：498K
• ISSN：1530-6992

文摘

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 a significant intensity change with sample orientations, and the behavior of angle-resolved phonon modes at the Γ point is explained by theoretical calculations. 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 a reduced thickness. A low-temperature Hall experiment sheds light on more intrinsic anisotropic electrical transport, with a hole mobility of 3000 and 1500 cm²/V·s along the a-axis and c-axis, respectively. Pronounced quantum oscillations in magnetoresistance are observed at low temperatures with the highest electron mobility up to 44 000 cm²/V·s.