Raman signatures of inversion symmetry breaking and structural phase transition in type-II Weyl semimetal MoTe<sub>2</sub>.
basic_science · Level V
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- Record sourced from PubMed, PMID 27934874.
- Also identified by DOI 10.1038/ncomms13552 and PMC identifier 5155143.
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Abstract
Transition metal dichalcogenide MoTe<sub>2</sub> is 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 MoTe<sub>2</sub> by 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 T<sub>d</sub> phase from vibrational spectroscopy, and suggest MoTe<sub>2</sub> as an ideal candidate for investigating the temperature-induced topological phase transition.