Competition between the Pseudogap and Superconducting States of Y-Bi2212 Single Crystals Revealed by Ultrafast Broadband Optical Reflectivity

Ultrafast broadband transient reflectivity experiments are performed to study the interplay between the non-equilibrium dynamics of the pseudogap and the superconducting phases in Y-Bi2212. Once superconductivity is established the relaxation of the pseudogap proceeds 2 times faster than in the normal state, and the corresponding transient reflectivity variation changes sign after 0.5 ps. The results can be described by a set of coupled differential equations for the pseudogap and for the superconducting order parameter. The sign and strength of the coupling term suggest a remarkably weak competition between the two phases, allowing their coexistence.