Superconductivity on the localization threshold and magnetic-field-tuned superconductor-insulator transition in TiN films

Abstract

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 Aslamazov-Larkin fluctuations is taken into account. This demonstrates the possibility of the 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 is equal to h/e 2.