From quantum corrections to magnetic-field-tuned superconductor–insulator quantum phase transition in TiN films

Abstract

Results of the measurements of the magnetic-field-dependent resistance of ultrathin superconducting TiN films with different degrees of disorder are presented. The main features of the isomagnetic data R ( T , B = const ) and isotherms R ( B , T = const ) observed in all samples are: fan-shaped structure of R ( T , B = const ) curves, a negative magnetoresistance at high magnetic fields, the presence of an intersection point ( B c , R c ), and the possibility of a scaling data presentation. The analysis of the data reveals that such behavior, previously regarded as the main evidence of the magnetic-field-tuned superconductor–insulator transition, can actually be observed for a usual thermodynamic superconductor–normal metal transition, provided that the behavior of this metal is controlled, to a considerable degree, by the quantum corrections to the conductivity.