Figure 1

(Color online) Temperature dependence of the Raman scattering spectra (a) of ${\text{DyTe}}_3$ at ambient pressure and (b) of ${\text{LaTe}}_3$ at 6 GPa. The spectra have been shifted for clarity. In panel (a) the oscillators employed for the data fits are shown for the measurement at 30 K (dotted lines) and the arrows mark the weak features at 113 and $143{\text{cm}}^{-1}$. The labels A and B denote the weak mode at $\sim 60{\text{cm}}^{-1}$ and the sharp one at $\sim 70{\text{cm}}^{-1}$ at low temperatures, respectively.Reuse & Permissions

Figure 2

(Color online) Detailed view of the temperature dependence of the A, B [see Fig. 1a], and C modes of ${\text{DyTe}}_3$ (a) above and (b) below $T_{tr}$. The arrows highlight the trend of modes A and B with increasing temperature. (c) Low-frequency interval characterized by mode D for temperatures close to and below $T_{\text{CDW}2}$. The relative intensity ratio among panels (a)–(c) is 2:8:1.Reuse & Permissions

Figure 3

(Color online) Temperature dependence [(a) and (b)] of the resonance frequencies and [(c) and (d)] of the normalized integrated intensities of the A (blue dot) and B (red square) modes of ${\text{DyTe}}_3$ at ambient pressure and of ${\text{LaTe}}_3$ at 6 GPa. The dashed lines at about $59\left(63\right){\text{cm}}^{-1}$ in panels (a) and (b) are the respective renormalized phonons which couple to the collective excitation. Panel (a) also reports the resonance frequencies of the C lattice mode (green triangle) and of the amplitude mode (D) for the bidirectional CDW of ${\text{DyTe}}_3$ [Fig. 2c]. The blue and red lines in panels (a) and (b) are the fits of the resonance frequencies for modes A and B (see text). The thin dotted lines in panels (a) and (c) and (d) are the BCS predictions for the resonance frequencies $\left[\omega \sim n_c\left(T\right)\right]$ and for the order parameter $\left[I_A\left(T\right)\sim \Delta \left(T\right)\right]$ (Refs. 1, 27), respectively. The normalization factor in panels (c) and (d) corresponds to the total intensity of both modes.Reuse & Permissions