Ultrafast Mid-Infrared Response of YBa ₂ Cu ₃ O _7-δ

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.

Many-body and correlation effects in semiconductors

“…High-T c superconductors, transition metal oxides and polymers are some examples of highly correlated systems. Some work in this direction has already begun 46,47 . Figure 7 Coherent response of GaAs in the quantum Hall regime.…”

Ultrafast pump-probe spectroscopic signatures of superconducting and pseudogap phases in YBa2Cu3O7−δ films

“…1,2 In the past, the experiments that probe the electronic properties at equilibrium have provided strong evidence for the coupling between QPs and bosonic excitations linked to lattice phonon modes and spin degrees of freedom. [1][2] Time-resolved spectroscopy with ultrafast temporal resolution is a complementary tool to investigate the temporal evolution of the QP-bosonic degrees of freedom [3][4][5][6][7][8] that is capable to disentangle the contribution of bosonic excitations from the dynamics viewpoint. 6 Based on this observation, the non-equilibrium optical spectroscopy has been extensively applied to explore mechanisms of phase separation, [9][10][11][12][13][14][15] boson pairing, 16 and the electron-phonon coupling [17][18][19][20][21] in superconductors by monitoring the QP dynamics; the experimental results are conventionally connected to microscopic processes by application of a phenomenological model proposed by Rothwarf and Taylor (i.e.…”

Kinetics of a Superconductor Excited with a Femtosecond Optical Pulse

“…Analytical solutions for various limiting cases are obtained. The model is found to account for the intensity and temperature dependence of both photoinduced quasiparticle density, as well as pair-breaking and superconducting state recovery dynamics in conventional as well as cuprate superconductors.In recent years numerous studies of non-equilibrium carrier dynamics in superconductors (SC) have been performed utilizing femtosecond real-time techniques [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18]. Research focused on the identification of relaxation processes and direct measurements of the relaxation times.…”