Dresden 2003 – scientific programme
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TT: Tiefe Temperaturen
TT 21: Phasendiagramm der HTSL
TT 21.5: Talk
Friday, March 28, 2003, 12:05–12:20, HSZ304
Phase sensitive evidence for a predominant d-wave symmetry in the electron doped superconductor LaCeCuO — •B. Chesca1, K. Ehrhardt1, M. Moessle1, R. Straub1, D. Kolle1, R. Kleiner1 und A. Tsukada2 — 1Physikalisches Institut-Experimentalphysik II, Universitaet Tuebingen, auf der Morgenstelle 14, D-72076 Tuebingen, Deutschland — 2Department of Physics, Science University of Tokyo, 1-3, Kagurazaka, Shinjuku-ku, Tokyo ,162-8601, Japan
Whereas for hole doped materials the d-wave symmetry has been established for the order parameter describing the pairing of electrons in the superconducting state, for electron doped superconductors the issue has not been yet fully understood. Phase sensitive experiments aimed to detect the half-flux quantum effect along with critical current versus magnetic field measurements of specially designed superconducting quantum interference devices (SQUIDs) are widely recognized to be most definitive tests. Here we report on the first successful phase sensitive test of the later type involving the electron doped cuprate LaCeCuO grown as a thin film on a SrTiO tetracrystal substrate [1]. The SQUIDs were patterned according to a design based on the concept of a spatially distributed junction configuration. The superconducting transition temperature was about 29 K which indicates that the sample is not far from the optimal doping. The magnetic field dependencies of the SQUIDs critical current gives strong evidence for a predominant d-wave symmetry of the superconducting order parameter of the particular sample measured. It also gives upper limits for the s wave component in a mixed order parameter of the type s+id. [1] B. Chesca at al., to be published in Phys.Rev.Lett.