Superconductivity in the cuprates is characterized by an anisotropic electronic gap of d-wave symmetry. The aim of this work is to understand how this anisotropy affects the nonequilibrium electronic response of high-Tc superconductors. Here we use a polarization selective time domain experiment to address the dynamics of electronic excitation of different symmetry in optimally doped Bi2Sr2Y0.08Ca0.92Cu2O8+δ and measure the nodal and antinodal nonequilibrium response resulting from photoexcitations with ultrashort pulses with photon energy comparable to the superconducting gap. The response to long wavelength photoexcitation with pump polarization along the Cu-Cu axis of the sample is discussed with the support of an effective d-wave BCS model which suggests that such transient response could be ascribed to an increase of pair coherence in the antinodal region.
Bibliographical noteFunding Information:
This work was mainly supported by the European Commission through the ERCStG2015, INCEPT, Grant No. 677488. A.A. acknowledges support by MIUR under Project No. PRIN 2017RKWTMY. This research was undertaken thanks in part to funding from the Max Planck UBC Centre for Quantum Materials and the Canada First Research Excellence Fund, Quantum Materials and Future Technologies Program. The work at UBC was supported by the Killam, Alfred P. Sloan, and Natural Sciences and Engineering Research Council of Canada (NSERC) Steacie Memorial Fellowships (A.D.), the Alexander von Humboldt Fellowship (A.D.), the Canada Research Chairs Program (A.D.), NSERC, Canada Foundation for Innovation (CFI), and CIFAR Quantum Materials Program. The work at the University of Minnesota was funded by the Department of Energy through the University of Minnesota Center for Quantum Materials under Grant No. DE-SC-0016371. D.F. acknowledges support by MIUR under Project No. PRIN 2017BZPKSZ.
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