Collective Charge Density Waves dynamics in YBCO revealed by ultrashort hard X-ray

The collective dynamics of complex phases such as stripes, charge density waves and high temperature superconductivity can provide useful insight on their origin and interactions. Ultrafast optical measurements have revealed coherent oscillations related phonons modes, as well as collective modes of the charge order in high temperature superconductors. However, optical probes can only detect a limited set of modes and unambiguous assignment is often challenging. Here, using ultrafast hard x-ray scattering, we present collective oscillations of the amplitude of the charge density wave (CDW) peak in underdoped YBCO. The CDW amplitude presents large oscillations at a central frequency of 2.2 THz. Additional modes will also be discussed.