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

Date
2019-03-07
Authors
Yang, Xu
Orth, Peter
Zhao, X.
Vaswani, Chirag
Sundahl, C.
Song, Boqun
Yao, Yong-Xin
Cheng, Di
Liu, Zhiyan
Orth, Peter
Mootz, M.
Kang, J. H.
Perakis, I. E.
Wang, Cai-Zhuang
Ho, Kai-Ming
Eom, C. B.
Wang, Jigang
Major Professor
Advisor
Committee Member
Journal Title
Journal ISSN
Volume Title
Publisher
Altmetrics
Authors
Orth, Peter
Person
Research Projects
Organizational Units
Ames Laboratory
Organizational Unit
Physics and Astronomy
Organizational Unit
Journal Issue
Series
Department
Ames LaboratoryPhysics and Astronomy
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 ℏω absorption to create QPs set by 2ΔSC/ℏω=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.

Comments
Description
Keywords
Citation
DOI
Collections