Fig. 4: Raman modes and phonon band structure in ScV6Sn6.
From: Phonon promoted charge density wave in topological kagome metal ScV6Sn6
a Temperature-dependent colormap of the Raman response recorded on ScV6Sn6. The inset illustrates the relationship between the soft mode and amplitude mode in typical CDW materials. The soft mode frequency (ωSM) freezes below TCDW, and the frequency (ωAM) emerges afterward. b Typical Raman spectra measured below and above TCDW. c Calculated Raman mode frequencies around Γ point. d Temperature-dependent Raman spectra illustrating the A3 mode. e Temperature dependence of the Frequency and linewidth of the A3 mode. The error bars represent the fit uncertainty. f DFT calculated phonon band structure along high-symmetry paths (i) and the K - H - K path (ii) of pristine ScV6Sn6, with experimental lattice parameters29. The red shaded region indicates the half frequency of the two-phonon mode. g Distortion pattern of the trihexagonal pattern in the 2 × 2 × 1 CDW phase of CsV3Sb5. h Acoustic phonon mode at the K point (i) corresponding to the observed two-phonon mode in a, or b; and distortion pattern of the \(\sqrt{3}\times\sqrt{3}\times3\) CDW (ii) indicated by the vectors, with respect to the pristine phase of ScV6Sn6 [Fig. 1a(i)]. The length of the vectors represents the amplitude of atomic displacements.
