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Ultrafast quasiparticle dynamics in Co-doped BaFe<sub>2</sub>As<sub>2</sub>

ORAL

Abstract

The understanding of excited state dynamics in iron-based superconductors is the subject of great interest in theoretical and experimental condensed matter physics. Here we report on time-domain studies of light-induced quasiparticle dynamics in Co-doped BaFe2As2 superconducting epitaxial thin films at different excitation regimes. The evolution of transient optical signal in superconducting and non-superconducting states reveals several regions with noticeably different electron-phonon relaxation. The most distinct dynamics associated with multi-stage quasiparticle relaxation rise up on a sub-30 ps time scale. The sub-500 fs process is associated with the instantaneous formation of the nonequilibrium state of quasiparticles. It is followed by the energy exchange between this photoexcited state and lattice with electron thermalization within 3 ps. The characteristic time of this process grows with excitation and is associated with the evolution of quasiparticles and, possibly, hidden phases. New mechanisms seem to underpin the photoinduced relaxation dynamics of Co-doped BaFe2As2 in low- and high-excitation regimes.

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Presenters

  • Sergiy Lysenko

    Department of Physics, University of Puerto Rico, Mayaguez, Puerto Rico 00681, USA, University of Puerto Rico at Mayagüez

Authors

  • Sergiy Lysenko

    Department of Physics, University of Puerto Rico, Mayaguez, Puerto Rico 00681, USA, University of Puerto Rico at Mayagüez

  • Alexander Bartenev

    Department of Physics, University of Puerto Rico, Mayaguez, Puerto Rico 00681, USA

  • Ki-Tae Eom

    University of Wisconsin - Madison, University of Wisconsin-Madison, Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, WI 53706, USA, University of Wisconsin Madison

  • Jong-Hoon Kang

    Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, WI 53706, USA

  • Roman Kolodka

    Department of Physics, University of Puerto Rico, Mayaguez, Puerto Rico 00681, USA

  • Eric E Hellstrom

    Applied Superconductivity Center, National High Magnetic Field Laboratory, Florida State University, 2031 East Paul Dirac Drive, Tallahassee, FL 32310, USA

  • Chang-Beom Eom

    Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, WI 53706, USA, University of Wisconsin-Madison, Department of Materials Science and Engineering, Madison, WI 53706, USA

  • Armando Rua

    Department of Physics, University of Puerto Rico, Mayaguez, Puerto Rico 00681, USA