Competing soft phonon modes at the charge-density-wave transitions in DyTe3

Abstract

The family of rare-earth tritellurides RTe3 features charge-density-wave (CDW) order related to strongly momentum-dependent electron-phonon coupling. Similar to other CDW compounds, superconductivity is observed when the CDW order is suppressed via hydrostatic pressure [1]. What sets the heavier members of the RTe3 series apart is the observation of a second CDW transition at lower temperatures having an in-plane ordering wavevector , ∥ [ ] of almost the same magnitude but orthogonal to the ordering wavevector , ∥ [ ] observed at higher temperatures [2]. Here, we report an inelastic x-ray scattering investigation of the lattice dynamics of DyTe3. In particular, we show that there are several phonon modes along both in-plane directions, which respond to the onset of the CDW transition at , =. Surprisingly, these soft modes close to , = ( . , , ) show strong softening near , but do not exhibit any response to the lower-temperature transition at , = . Our results indicate that the low-temperature CDW order is not just the 90° rotated analogue of the one appearing at high temperatures.

Soft-phonon driven hexagonal-orthorhombic phase transition in BaVS3

“…Upon further cooling below T S , the intrinsic width increases back. This can be explained by the soft-phonon hardening after the settling of the orthorhombic transition, as observed in other compounds 25,26 . Some electronphonon coupling mechanism could be involved, the study of which lies outside the scope of this work.…”

Amplitude dynamics of the charge density wave in LaTe3 : Theoretical description of pump-probe experiments

“…Theoretically, we apply small-oscillations formalism [54,55] to the TDGL equations (12) and (15), see Appendix B for detailed derivations. On the experimental side, the phonon spectrum in RTe 3 and its temperature dependence were reported in many works [8,47,49,79,80].…”

“…8(a,c) in Ref. 80] softens to zero close to the transition temperature. Thus, we assume the adiabatic regime for LaTe 3 as well.…”

Light-induced charge density wave in LaTe3

“…We can gain some insight into the origin of the anoma- lous wavevector from previous inelastic X-ray scattering measurements and density functional theory calculations on DyTe 3 , which is in the same CDW family [20]. In DyTe 3 , when the c-axis CDW develops at 308 K, strong CDW fluctuations are also seen along the a-direction in the form of phonon softening, namely, a marked decrease in the phonon frequency.…”

“…[12] at the highest temperature below Tc1. For qa, only TbTe3 [21], DyTe3 [20], and ErTe3 [19] were accurately measured by X-ray diffraction (see Supplementary Note 3 for a discussion on the temperature dependence of qc and qa at equilibrium). White square denotes the calculated wavevector of the soft phonon along the a-axis, which was confirmed by inelastic X-ray scattering at Tc1 [20].…”