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TT: Fachverband Tiefe Temperaturen
TT 30: Superconductivity - Poster Session
TT 30.19: Poster
Montag, 31. März 2014, 15:00–19:00, P2
Magnetic-field-dependent reentrant superconductivity in Ga-implanted Si — •R. Skrotzki, T. Herrmannsdörfer, R. Schönemann, V. Heera, J. Fiedler, E. Kampert, F. Wolff-Fabris, T. Förster, M. Voelskow, A. Mücklich, B. Schmidt, W. Skorupa, M. Helm, and J. Wosnitza — Hochfeld-Magnetlabor Dresden (HLD) und Institut für Ionenstrahlphysik und Materialforschung, Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Dresden, Germany
We have implanted Ga ions into Si wafers and thereby formed 10 nm thin films of densely-packed amorphous Ga clusters. Via short-term annealing we are able to trigger a structural superconductor-insulator transition. On its superconducting side (Tc ≈ 7 K), we observe a reentrant transition where zero resistance is intermitted by finite resistance at 0.1 K < T < 1 K. This phenomenon is accompanied by non-linear current-voltage characteristics and suppressed at in- and out-of-plane oriented magnetic fields H > Hreentrant. Moreover, we find that Hreentrant accounts for up to 10 T and reveals the same anisotropy as Hc2 indicating a strong dependence on the vortex density in this non-magnetic material. A detailed phase diagram is drawn from magneto-transport measurements in high magnetic fields of more than 40 T. We assume that fluctuations are responsible for paraconductivity of 2D Aslamazov-Larkin type at T > Tc as well as for the reentrant phenomenon at T < Tc. The latter we discuss in terms of thermally activated phase-slip processes in conjunction with transport dynamics of resistively and capacitively shunted superconducting tunnel networks.