Regensburg 2016 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 19: Superconductivity: Poster Session
TT 19.32: Poster
Montag, 7. März 2016, 15:00–18:00, Poster D
Measurement of the Magnetic Penetration Depth in p-Doped Superconducting Diamond Films — •Lorenz Fuchs1, Markus C.P. Brunner1, Ina Schneider1, Klaus Kronfeldner1, Jessica Bousquet2, Etienne Bustarret2, and Christoph Strunk2 — 1University of Regensburg — 2Institut Néel, Grenoble
Boron-doped diamond becomes superconducting once a critical doping concentration of 4.5 × 1020cm−3 is reached [1]. Mutual inductance measurements with a two-coil setup have been performed to determine the magnetic penetration depth λ(T), which is a measure for the superfluid stiffnes θ ∼ 1/λ2(T). Two superconducting p-doped diamond films with thicknesses of 145nm and 345nm were investigated. At low temperatures these values agree reasonably with the values expected within BCS-theory using Tc, carrier density and mean free path determined from electric transport measurements. Magnetic penetration depths of 3.7µ m for the thinner and 2.6µ m for the thicker film have been found. λ decreases and accordingly θ increases with increasing film thickness. On the other hand, the superfluid stiffness drops by a factor of 2 or even more at Tc/2, i.e., much faster than expected from BCS-theory, but remains finite between Tc/2 < T < Tc. At present it is unclear, whether this behavior results from the proliferation of phase fluctuations already far below Tc or from a spatial inhomogeneity of the films.