Regensburg 2007 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 10: Superconductivity - Properties, Electronic Structure, Order Parameter
TT 10.7: Talk
Tuesday, March 27, 2007, 11:00–11:15, H18
Terahertz spectroscopy of electron-doped superconductors in magnetic field — •Artem V. Pronin1, Andrei Pimenov2,3, Alois Loidl2, Akio Tsukada4,5, and Micho Naito4 — 1Hochfeld-Magnetlabor Dresden (HLD), Forschungszentrum Dresden-Rossendorf, 01314 Dresden, Germany — 2Experimentalphysik V, EKM, Universität Augsburg, 86135 Augsburg, Germany — 3Experimentelle Physik 4, Universität Würzburg, 97074 Würzburg, Germany — 4Department of Applied Physics, Tokyo University of Agriculture and Technology, 2-24-16, Naka-cho, Koganei, Tokyo 184-8588, Japan — 5NTT Basic Research Laboratories, NTT Corporation, 3-1 Morinosato-Wakamiya, Atsugi, Kanagawa 243-0198, Japan
In the terahertz and infrared regions we measured the optical conductivity and penetration depth of the electron-doped cuprate superconductor La2−xCexCuO4. In the frequency-temperature behavior of conductivity we observe remarkable differences between the samples with different Ce content, suggesting the gap anisotropy to be a function of the doping level.
At terahertz frequencies, we performed measurements in high magnetic fields to suppress superconductivity below Tc. From the conductivity spectra we extract the quasiparticle scattering rate as a function of temperature, and compare its behavior in the superconducting and normal states below Tc. We find a small but measurable optical magnetoresistance at all doping levels, and no signatures for the pseudogap. We also discuss the applicability of "universal scaling laws" to our data on conductivity and penetration depth.