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Volume 6 Research & Reviews: Journal of Material Sciences
ISSN: 2321-6212 Magnetic Materials 2018
October 22-23, 2018
Page 60
conferenceseries.com
October 22-23, 2018 | Rome, Italy
3rd International Conference on
Magnetism and Magnetic Materials
Christelle Kadlec, Res. Rev. J Mat. Sci. 2018, Volume 6
DOI: 10.4172/2321-6212-C6-028
Departure from BCS response in photoexcited superconducting films observed by terahertz
spectroscopy
We investigate thin superconducting NbN films with various thicknesses by time-resolved terahertz spectroscopy. In
agreement with previous reports, the equilibrium THz conductivity can be described by the BCS theory. Upon strong
photoexcitation by femtosecond laser pulses, when the superconducting state is completely broken, the recovery dynamics occurs
by a growth of initially spherical isolated superconducting islands in the normal-state environment. These islands subsequently
merge towards a nearly percolated superconducting network. The recovery process is accompanied by a shift in the conductivity
spectral weight, indicating a departure from the BCS character of the density of electron states in these islands. While the
superconductivity recovers on the hundreds-picosecond time scale, the properties characterizing the superconducting state (such
as the gap width and the density of states) recover much more slowly, at least on the nanosecond time scale.
Recent Publications
1. Matsunaga R and Shimano R (2012) Nonequilibrium BCS state dynamics induced by Intense terahertz pulses in a
superconducting NbN film. Physical Review Letters 109, 187002.
2. Beck M, Rousseau I, Klammer M, Leiderer P, Mittendorff M, Winnerl S, Helm M, Goltsman GN and Demsar J (2013)
Transient increase of the energy gap of superconducting NbN thin films excited by resonant narrow-band terahertz
pulses. Physical Review Letters 110, 267003.
3. Kabanov V V, Demsar J and Mihailovic D (2005) Kinetics of a superconductor excited with a femtosecond optical pulse.
Physical Review Letters 95, 147002.
4. Averitt R D and Taylor A J (2002) Ultrafast optical and far-infrared quasiparticle dynamics in correlated electron
materials. Journal of Physics-Condensed Matter 14, R1357.
Biography
Christelle Kadlec obtained her PhD in Plasma Physics from the University of Orleans, France. She works as a Researcher in the Institute of Physics in Prague, Czech
Republic in the field of THz spectroscopy, where she is considered as an expert in thin films. She is a co-author of more than 60 publications.
Christelle Kadlec
Institute of Physics, Czech Academy of Sciences, Czech Republic