Reveal Atomic Phase Transition via Nanomechanical Resonator

The diverse interactions between lattice symmetry and layer stacking orders make transition metal dichalcogenides (TMDs) especially potentially effective to detect for investigating novel topological states and quantum phase transitions. A case in point is transition metal dichalcogenides, notable for its diverse phases: hexagonal (2H, α-phase), monoclinic (1T′, β-phase), and orthorhombic (Td, γ-phase). The 2H phase exhibits semiconductors behavior while the 1T' phase and Td phase is semimetal. Current approaches to reveal the phase transition between those phases are limited to electrical and optical approaches, in which the contrast is low [1]. For example, the 1T′ and Td phases are structurally commensurate[2]-[4], in which the structural difference refers to layer-to-layer stacking orders. In this experimental study, the phase transitions in transition metal dichalcogenides is studied by nanomechanical resonators. Phase transition is clearly revealed by the frequency shift of the resonators. Modeling has been established to qualitatively correlate the frequency of the nanomechanical resonator with the phase change. Accompanied by a high-quality factor exceeding 1000, the high sensitivity of the resonator shows small sliding transition,providing the possibility of the new application degree for 2D resonators combining with materials’ phase diagram investigation and the potentiality to extract the thermodynamics information during the phase transition.<br/>[1] Qi, Y., Naumov, P., Ali, M. et al. Superconductivity in Weyl semimetal candidate MoTe2. Nat Commun 7, 11038 (2016). https://doi.org/10.1038/ncomms11<br/>[2] H. P. Hughes and R. H. Friend, “Electrical resistivity anomaly in β-MoTe 2 (metallic behaviour),” J. Phys. C Solid State Phys., vol. 11, no. 3, pp. L103–L105, Feb. 1978, doi: 10.1088/0022-3719/11/3/004.<br/>[3] K. Zhang et al., “Raman signatures of inversion symmetry breaking and structural phase transition in type-II Weyl semimetal MoTe2,” Nat. Commun., vol. 7, no. 1, p. 13552, Dec. 2016, doi: 10.1038/ncomms13552.<br/>[4] S.-Y. Chen, T. Goldstein, D. Venkataraman, A. Ramasubramaniam, and J. Yan, “Activation of New Raman Modes by Inversion Symmetry Breaking in Type II Weyl Semimetal Candidate T′-MoTe2,” Nano Lett., vol. 16, no. 9, pp. 5852–5860, Sep. 2016, doi: 10.1021/acs.nanolett.6b02666.