Regensburg 2010 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 20: SC: Fabrication and Characterization of Iron-Based and Other Superconductors
TT 20.12: Vortrag
Mittwoch, 24. März 2010, 12:30–12:45, H19
Effect of Gallium Doping on Superconductivity in Germanium — •R. Skrotzki1, T. Herrmannsdörfer1, V. Heera2, O. Ignatchik1, M. Uhlarz1, A. Mücklich2, M. Posselt2, H. Reuther2, B. Schmidt2, K.-H. Heinig2, W. Skorupa2, M. Voelskow2, C. Wündisch2, J. Fiedler2, M. Helm2, and J. Wosnitza1 — 1Hochfeld-Magnetlabor Dresden, Forschungszentrum Dresden-Rossendorf (FZD) — 2Institut für Ionenstrahlphysik und Materialforschung, FZD
We report recent discoveries of superconductivity in Ga-doped germanium fabricated by ion implantation and subsequent flash-lamp or oven annealing. Tuning the preparation parameters allows for varying both charge-carrier and Ga concentration in the resulting roughly 100 nm thin nano- or single-crystalline layers. Transport measurements on systematically prepared samples reveal that besides a needed charge-carrier concentration of more than 0.4 atom%, superconductivity occurs to be sensitive on the implanted Ga content which may also be attributed to a change in the phonon properties. Onset transition temperatures up to 1.4 K have been found for almost 10 atom% Ga. Further, we observe in-plane critical fields exceeding 1 T and being close to the Pauli-Clogston limit. An exceptionally low Cooper-pair density of around 1015 cm−3 turns out the extreme type-II character of superconductivity. Finally, our work adds to our previous report [1] and may help to understand superconductivity in doped elemental semiconductors in general.
T. Herrmannsdoerfer et. al., Phys. Rev. Lett. 102, 1027003 (2009)