“…Raman spectroscopy is an experimental technique which is directly sensitive to the crystal structure. [ 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 ] Previous Raman spectroscopy studies of the bulk 1 T ′‐MoTe 2 crystals indicate that in the high‐temperature 1 T ′ phase at T ≥ 250 K upon cooling (or at T ≥ 260 K upon warming), the out‐of‐plane vibration mode D around 125 cm –1 is Raman in‐active (i.e., only infrared active) and is absent in the Raman spectra due to the centrosymmetry of the monoclinic 1 T ′ structure, while in the low‐temperature T d phase at T < 250 K upon cooling (or at T < 260 K upon warming), the out‐of‐plane vibration mode D becomes both Raman‐ and infrared‐active and can be probed by Raman spectroscopy owing to the centrosymmetry breaking in the orthorhombic T d structure (see the two vibration modes D and E in the Raman spectra of the MoTe 2 bulk crystal with the orthorhombic T d structure measured at T = 80 K in Figure 2 a , the vibration mode e in the Raman spectra of the MoTe 2 bulk crystal with the monoclinic 1 T ′ structure at T = 300 K in Figure 2b , and the Raman spectra of the MoTe 2 bulk crystal in the energy range from 60 to 300 cm –1 in Figure S1 , Supporting Information). [ 35 , 36 , 37 , 38 , 39 , 40 ] Thus, the presence of the out‐of‐plane vibration mode D can be regarded as a spectroscopic signature of the temperature‐driven structural phase transition in MoTe 2 from the high‐temperature monoclinic 1 T ′ structure to the low‐temperature orthorhombic T d structure.…”