title: Observation of Optical and Electrical In-Plane Anisotropy in High-Mobility Few-Layer ZrTe5.
abstract: Transition metal pentatelluride ZrTe5is a versatile material in condensed-matter physics and has been intensively studied since the 1980s. The most fascinating feature of ZrTe5is that it is a 3D Dirac semimetal which has linear energy dispersion in all three dimensions in momentum space. Structure-wise, ZrTe5is 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 ZrTe5related 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.
authors.affiliation: School of Electrical and Computer Engineering, ‡School of Industrial Engineering, §School of Mechanical Engineering, and ∥Birck Nanotechnology Center, Purdue University , West Lafayette, Indiana 47907, United States.
authors.forename: Gang
authors.initials: G
authors.lastname: Qiu
authors.affiliation: School of Electrical and Computer Engineering, ‡School of Industrial Engineering, §School of Mechanical Engineering, and ∥Birck Nanotechnology Center, Purdue University , West Lafayette, Indiana 47907, United States.
authors.forename: Yuchen
authors.initials: Y
authors.lastname: Du
authors.affiliation: School of Electrical and Computer Engineering, ‡School of Industrial Engineering, §School of Mechanical Engineering, and ∥Birck Nanotechnology Center, Purdue University , West Lafayette, Indiana 47907, United States.
authors.forename: Adam
authors.initials: A
authors.lastname: Charnas
authors.affiliation: School of Electrical and Computer Engineering, ‡School of Industrial Engineering, §School of Mechanical Engineering, and ∥Birck Nanotechnology Center, Purdue University , West Lafayette, Indiana 47907, United States.
authors.forename: Hong
authors.initials: H
authors.lastname: Zhou
authors.affiliation: School of Electrical and Computer Engineering, ‡School of Industrial Engineering, §School of Mechanical Engineering, and ∥Birck Nanotechnology Center, Purdue University , West Lafayette, Indiana 47907, United States.
authors.forename: Shengyu
authors.initials: S
authors.lastname: Jin
authors.affiliation: School of Electrical and Computer Engineering, ‡School of Industrial Engineering, §School of Mechanical Engineering, and ∥Birck Nanotechnology Center, Purdue University , West Lafayette, Indiana 47907, United States.
authors.forename: Zhe
authors.initials: Z
authors.lastname: Luo
authors.affiliation: School of Electrical and Computer Engineering, ‡School of Industrial Engineering, §School of Mechanical Engineering, and ∥Birck Nanotechnology Center, Purdue University , West Lafayette, Indiana 47907, United States.
authors.forename: Dmitry Y
authors.initials: DY
authors.lastname: Zemlyanov
authors.affiliation: School of Electrical and Computer Engineering, ‡School of Industrial Engineering, §School of Mechanical Engineering, and ∥Birck Nanotechnology Center, Purdue University , West Lafayette, Indiana 47907, United States.
authors.forename: Xianfan
authors.initials: X
authors.lastname: Xu
authors.affiliation: School of Electrical and Computer Engineering, ‡School of Industrial Engineering, §School of Mechanical Engineering, and ∥Birck Nanotechnology Center, Purdue University , West Lafayette, Indiana 47907, United States.
authors.forename: Gary J
authors.initials: GJ
authors.lastname: Cheng
authors.affiliation: School of Electrical and Computer Engineering, ‡School of Industrial Engineering, §School of Mechanical Engineering, and ∥Birck Nanotechnology Center, Purdue University , West Lafayette, Indiana 47907, United States.
authors.forename: Peide D
authors.initials: PD
authors.lastname: Ye
keywords: 2D material; ZrTe5 single crystal; electrical anisotropy; optical anisotropy; quantum oscillations