Observation of Competing Order in a High-T_c Superconductor Using Femtosecond Optical Pulses

摘要

We present studies of the photoexcited quasiparticle dynamics in Tl_2Ba_2Ca_2Cu_3O_5. (Ti-2223) using femtosecond optical techniques. Deep into the superconducting state (below 40 K). a dramatic change occurs in the temporal dynamics associated with photoexcited quasiparticles rejoining the condensate. This is suggestive of entry into a coexistence phase which, as our analysis reveals, opens a gap in the density of states (in addition to the superconducting gap), and furthermore, competes with superconductivity resulting in a depression of the superconducting gap.