Regensburg 2002 – scientific programme

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TT: Tiefe Temperaturen

TT 6: Supraleitung: Elektronenstruktur, Phononen, Tunneln, Ordnungsparameter I

TT 6.6: Talk

Monday, March 11, 2002, 17:15–17:30, H19

Low-frequency electrodynamics of La₂Ce_2−xCuO₄ — •Artem Pronin¹, Andrei Pimenov¹, Alois Loidl¹, Akio Tsukada², and Michio Naito² — ¹Experimentalphysik V, EKM, Universitaet Augsburg — ²NTT Basic Research Laboratories, Kanagawa, Japan

We measure the complex conductivity of LaCeCu-oxide superconductors in the millimeter and submillimeter frequency domain (5 - 40 cm⁻¹) and for temperatures 2 K < T < 300 K. High quality films on transparent substrates are used for the amplitude and phase-shift transmittance measurements. The tilted geometry of the substrate allows to determine both in- and out-of-plane response. The normal-state conductivity is governed mainly by a Drude-mode, which narrows for decreasing temperature. In the superconducting state the width of the Drude peak collapses, leading to a vanishing real part of the in-plane conductivity. We discuss the temperature and frequency behavior of the relaxation rate for several samples with different doping concentrations. The c-axes response below T_c is dominated by the Josephson plasma resonance.