title: Ultrafast mid-infrared response of YBa(2)Cu(3)O(7-delta)
abstract: Optical spectra of high-transition-temperature superconductors in the mid-infrared display a gap of in-plane conductivity whose role for superconductivity remains unresolved. Femtosecond measurements of the mid-infrared reflectivity of YBa(2)Cu(3)O(7-delta) after nonequilibrium optical excitation are used to demonstrate the ultrafast fill-in of this gap and reveal two gap constituents: a picosecond recovery of the superconducting condensate in underdoped and optimally doped material and, in underdoped YBa(2)Cu(3)O(7-delta), an additional subpicosecond component related to pseudogap correlations. The temperature-dependent amplitudes of both contributions correlate with the antiferromagnetic 41-millielectronvolt peak in neutron scattering, supporting the coupling between charges and spin excitations.
authors.affiliation: Max-Born-Institut fur Nichtlineare Optik und Kurzzeitspektroskopie, D-12489 Berlin, Germany. Department of Physics, Clarendon Laboratory, Oxford University, Oxford OX1 3PU, UK. Department of Pure and Applied Physics, Queen's University of Belfast.
authors.initials: RA
authors.lastname: Kaindl
authors.initials: M
authors.lastname: Woerner
authors.initials: T
authors.lastname: Elsaesser
authors.initials: DC
authors.lastname: Smith
authors.initials: JF
authors.lastname: Ryan
authors.initials: GA
authors.lastname: Farnan
authors.initials: MP
authors.lastname: McCurry
authors.initials: DG
authors.lastname: Walmsley