He, Y.; Wu, S.; Song, Y.; Lee, W.; Said, A.; Alatas, A.; Bosak, A.; Girard, A.; Souliou, S.; Ruiz, A.; Hepting, M.; Bluschke, M.; Schierle, E.; Weschke, E.; Lee, J.; Jang, H.; Huang, H.; Hashimoto, M.; Lu, D.; Song, D.; Yoshida, Y.; Eisaki, H.; Shen, Z.; Birgeneau, R.; Yi, M.; Frano, A.: Persistent low-energy phonon broadening near the charge-order q vector in the bilayer cuprate Bi2Sr2CaCu2O8+δ. Physical Review B 98 (2018), p. 035102/1-10
10.1103/PhysRevB.98.035102

Abstract:
We report a persistent low-energy phonon broadening around qB∼0.28 reciprocal lattice unit (r.l.u.) along the Cu-O bond direction in the high- Tc cuprate Bi2Sr2CaCu2O8+δ (Bi-2212). We show that such broadening exists both inside and outside the conventional charge-density wave (CDW) phase, via temperature-dependent measurements in both underdoped and heavily overdoped samples. Combining inelastic hard x-ray scattering, diffuse scattering, angle-resolved photoemission spectroscopy, and resonant soft x-ray scattering at the Cu L3 -edge, we exclude the presence of a CDW in the heavily overdoped Bi-2212 similar to that observed in the underdoped systems. Finally, we discuss the origin of such anisotropic low-energy phonon broadening and its potential precursory role to the CDW phase in the underdoped region.