Energy dependence of the electron-boson coupling strength in the electron-doped cuprate superconductor Pr1.85Ce0.15CuO4-delta

Article

关键词: TRANSITION-TEMPERATURE SUPERCONDUCTOR;    FEMTOSECOND SPECTROSCOPY;    RELAXATION;    DYNAMICS;    DISTRIBUTIONS;    FLUCTUATIONS;    PR2-XCEXCUO4;    LIFETIMES;    FILMS;    GOLD;   

DOI  :  10.1103/PhysRevB.95.085106

来源: SCIE

【 摘 要 】

The quest for a pairing boson in cuprate high-temperature superconductors is one of the outstanding tasks of solid-state physics. Numerous time-resolved studies of pair breaking, related to pairing by time-reversal symmetry, have been performed using femtosecond optical pulses. By considering energy relaxation pathways between charge, spin, and lattice degrees of freedom, evidence for both phonon and antiferromagnetic fluctuation-mediated pairing has been obtained. Here we present a study of the superconducting-state depletion process in an electron-doped cuprate Pr1.85Ce0.15CuO4-delta, where the superconducting gap is smaller than the energy of relevant bosonic excitations. When pumping with above-gap terahertz pulses, we find that the absorbed energy density required to deplete superconductivity, A(dep), matches the thermodynamic condensation energy. On the contrary, by near-infrared pumping, A(dep) is an order of magnitude higher, as in the case of hole-doped, large-gap cuprates. These results imply that only a small subset of bosons, which are generated during the relaxation of optically excited carriers, contributes to pairing. This observation implies that, contrary to the common assumptions, electron-boson coupling in cuprates is strongly energy dependent.

【 授权许可】

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