Critical flux pinning and enhanced upper-critical-field in magnesium diboride films

Abstract

We have conducted pulsed transport measurements on c-axis oriented magnesium diboride films over the entire relevant ranges of magnetic field $0 \alt H \alt H_{c2}$ (where \hcu is the upper critical field) and current density $0 \alt j \alt j_{d}$ (where $j_d$ is the depairing current density). The intrinsic disorder of the films combined with the large coherence length and three-dimensionality, compared to cuprate superconductors, results in a six-fold enhancement of $H_{c2}$ and raises the depinning current density $j_c$ to within an order of magnitude of $j_d$. The current-voltage response is highly non-linear at all fields, resulting from a combination of depinning and pair-breaking, and has no trace of an Ohmic free-flux-flow regime. Keywords: pair, breaking, depairing, superconductor, superconductivity, flux, fluxon, vortex, mgb2

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Cited by in corpus (4)

• Upper critical field in nanostructured Nb: Competing effects of the reduction in density of states and the mean free path
• Current-Induced Pair Breaking in Magnesium Diboride
• Systematic characterization of upper critical fields for MgB${}_2$ thin films using the two-band superconducting theory
• Fast Dynamics of Vortices in Superconductors