Ultrafast nonthermal terahertz electrodynamics and possible quantum energy transfer in the Nb3Sn superconductor

Academic Article

Abstract

  • We report terahertz (THz) electrodynamics of a moderately clean A15 superconductor (SC) following ultrafast excitation to manipulate quasiparticle (QP) transport. In the Martensitic normal state, we observe a photo enhancement in the THz conductivity using optical pulses, while the opposite is observed for the THz pump. This demonstrates wavelength-selective nonthermal control of conductivity distinct from sample heating. The photo enhancement persists up to an additional critical temperature, above the SC one, from a competing electronic order. In the SC state, the fluence dependence of pair-breaking kinetics together with an analytic model provides an implication for a "one photon to one Cooper pair" nonresonant energy transfer during the 35-fs laser pulse; i.e., the fitted photon energy ω absorption to create QPs set by 2ΔSC/ω=0.33%. This is more than one order of magnitude smaller than in previously studied BCS SCs, which we attribute to strong electron-phonon coupling and possible influence of phonon condensation.
  • Authors

    Published In

  • Physical Review B  Journal
  • Digital Object Identifier (doi)

    Author List

  • Yang X; Zhao X; Vaswani C; Sundahl C; Song B; Yao Y; Cheng D; Liu Z; Orth PP; Mootz M
  • Volume

  • 99
  • Issue

  • 9