title: Raman signatures of inversion symmetry breaking and structural phase transition in type-II Weyl semimetal MoTe2.
abstract: Transition metal dichalcogenide MoTe2is an important candidate for realizing the newly predicted type-II Weyl fermions, for which the breaking of the inversion symmetry is a prerequisite. Here we present direct spectroscopic evidence for the inversion symmetry breaking in the low-temperature phase of MoTe2by systematic Raman experiments and first-principles calculations. We identify five lattice vibrational modes that are Raman-active only in the low-temperature noncentrosymmetric structure. A hysteresis is also observed in the peak intensity of inversion symmetry-activated Raman modes, confirming a temperature-induced structural phase transition with a concomitant change in the inversion symmetry. Our results provide definitive evidence for the low-temperature noncentrosymmetric Tdphase from vibrational spectroscopy, and suggest MoTe2as an ideal candidate for investigating the temperature-induced topological phase transition.
authors.affiliation: State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics,Tsinghua University, Beijing 100084, China.
authors.forename: Kenan
authors.initials: K
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics,Tsinghua University, Beijing 100084, China.
authors.forename: Changhua
authors.initials: C
authors.lastname: Bao
authors.affiliation: International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China.
authors.forename: Qiangqiang
authors.initials: Q
authors.lastname: Gu
authors.affiliation: International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China.
authors.forename: Xiao
authors.initials: X
authors.lastname: Ren
authors.affiliation: State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics,Tsinghua University, Beijing 100084, China.
authors.forename: Haoxiong
authors.initials: H
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics,Tsinghua University, Beijing 100084, China.
authors.forename: Ke
authors.initials: K
authors.lastname: Deng
authors.affiliation: State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics,Tsinghua University, Beijing 100084, China.|Tsinghua-Foxconn Nanotechnology Research Center, Tsinghua University, Beijing 100084, China.
authors.forename: Yang
authors.initials: Y
authors.lastname: Wu
authors.affiliation: International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China.|Collaborative Innovation Center of Quantum Matter, Beijing, China.
authors.forename: Yuan
authors.initials: Y
authors.lastname: Li
authors.affiliation: International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China.|Collaborative Innovation Center of Quantum Matter, Beijing, China.
authors.forename: Ji
authors.identifier: http://orcid.org/0000-0003-1944-718X
authors.initials: J
authors.lastname: Feng
authors.affiliation: State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics,Tsinghua University, Beijing 100084, China.|Collaborative Innovation Center of Quantum Matter, Beijing, China.
authors.forename: Shuyun
authors.initials: S
authors.lastname: Zhou