Superconductivity and hall effect of polycrystalline Pb82Bi18 thin films, a universal test platform for flux pinning by hybrid nanostructures

Abstract

We report the properties of superconductivity and Hall effect in 100 nm Pb[Formula: see text]Bi[Formula: see text] alloy thin films which were prepared by thermal evaporation with quench condensation using liquid nitrogen. X-ray diffraction indicates the films are [Formula: see text]-phase with peaks shifted to lower angles compared to pure Pb. The [Formula: see text] of the films was higher than those of an amorphous Pb–Bi alloy thin film of the same composition and pure bulk Pb. The resistivity, critical field and critical current density of the thin films are reported. The coherence length ([Formula: see text][Formula: see text]) and London penetration depth ([Formula: see text]) near [Formula: see text] were calculated from the experimental results. The films are in the dirty limit and behave as type-II superconductors with a Ginzburg–Landau parameter of about 10. Additionally, the films show sign reversal in Hall measurements. These films have been quite useful in a comprehensive study of the effects of flux pinning by integrated ferromagnetic nanostructures conducted in hybrid ferromagnet–superconductor samples in our lab over the past few years due to their single-phase nature and strong type-II behavior.