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TT: Fachverband Tiefe Temperaturen

TT 36: Superconductivity: Properties, Electronic Structure, Order Parameter

TT 36.10: Vortrag

Freitag, 29. Februar 2008, 12:45–13:00, H 0104

Localized superconductivity in TiN thin films — •Ante Bilušić¹, Tatyana Baturina², Tatyana Mironov², Florian Otto¹, Mikhaïl Baklanov³, and Christoph Strunk¹ — ¹Institute for Experimental and Applied Physics, University of Regensburg, Germany — ²Institute of Semiconductor Physics, Novosibirsk, Russia — ³IMEC, Leuven, Belgium

We present a low-temperature investigation of transport and magnetic properties of TiN thin films in the critical region of the disorder driven superconductor-insulator transition (SIT). At zero magnetic field, the superconducting and insulating phases are sharply separated, indicating the absence of the intermediate metallic state in the SIT. Electrical conductivity of the insulating films is thermally activated. Films closer to the critical level of disorder show a huge positive magnetoresistance (MR) at low, and a negative MR for high fields. Films being deeper on the insulating side of the SIT critical region exhibit negative MR only. At low temperatures, differential conductance curves of insulating samples show a depinning threshold V_T, below which the conductance is immeasurably small. Threshold V_T depends in a nonmonotonic way on magnetic field. This can be explained in terms of recent theory [1], which relies on the competition of Coulomb charging and Josephson coupling in arrays of Josephson junctions.

.1 cm [1] M. V. Fistul, V. M. Vinokur, and T. I. Baturina, arXiv:0708.2334v2 (unpublished)