Dresden 2014 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 30: Superconductivity - Poster Session
TT 30.9: Poster
Monday, March 31, 2014, 15:00–19:00, P2
Photo-induced quasipersistent modification of the normal and superconducting properties of niobium thin films — •Daniel Kohlberger1, Daniel Bothner1, Elisabeth Koroknay2, Michael Jetter2, Peter Michler2, Reinhold Kleiner1, and Dieter Koelle1 — 1Physikalisches Institut and Center for Collective Quantum Phenomena in LISA+, Universität Tübingen, Germany — 2Institut für Halbleiteroptik und Funktionelle Grenzflächen and Research Center SCoPE, Universität Stuttgart, Germany
We report on the experimental investigation of resistive and superconducting transport properties of niobium thin films, which have been irradiated with an infrared laser at cryogenic temperatures. After irradiation, we find an increased normal state resistivity and a reduced transition temperature Tc to the superconducting state with respect to the values before irradiation. This photo-induced modification is completely reversible by raising the sample temperature to T > 60 K, but remains unchanged over large timescales at lower temperatures. In addition, we demonstrate that by a spatially periodic variation of the laser intensity across the niobium film, the reported effect can be used to generate a periodic pinning potential for Abrikosov vortices at T < Tc. This periodic potential is revealed by the occurrence of matching features in the dependence of the critical current Ic on an applied magnetic field B after laser irradiation. Finally, we discuss possible mechanisms of the observed effect.