Superconductivity on the localization threshold and magnetic-field-tuned superconductor-insulator transition in TiN films
T. I. Baturina, D. R. Islamov, J. Bentner×, C. Strunk×, M. R. Baklanov+, A. Satta+
Institute of Semiconductor Physics, 630090 Novosibirsk, Russia
×Institut für experimentelle und angewandte Physik, Universität Regensburg, D-93025 Regensburg, Germany
+Independent Microelectronic Center, B-3001 Leuven, Belgium
PACS: 71.30.+h, 74.25.-q, 74.40.+k
Abstract
Temperature- and magnetic-field dependent measurements of the
resistance of ultrathin superconducting TiN films are presented. The analysis
of the temperature dependence of the zero field resistance indicates an
underlying insulating behavior, when the contribution of Aslamasov-Larkin
fluctuations is taken into account. This demonstrates the possibility of
coexistence of the superconducting and insulating phases and of a direct
transition from the one to the other. The scaling behavior of magnetic field
data is in accordance with a superconductor-insulator transition (SIT) driven
by quantum phase fluctuations in two-dimensional superconductor. The
temperature dependence of the isomagnetic resistance data on the high-field
side of the SIT has been analyzed and the presence of an insulating phase is
confirmed. A transition from the insulating to a metallic phase is found at
high magnetic fields, where the zero-temperature asymptotic value of the
resistance being equal to h/e2.