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

M. N. Kunchur·C. Wu·D. H. Arcos·B. I. Ivlev·Eun-Mi Choi·Kijoon H. P. Kim·W. N. Kang·Sung-Ik Lee
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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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M. N. Kunchur, C. Wu, D. H. Arcos, B. I. Ivlev, Eun-Mi Choi, Kijoon H. P. Kim, W. N. Kang, Sung-Ik Lee. 2003-11-15. Critical flux pinning and enhanced upper-critical-field in magnesium diboride films. https://doi.org/10.1103/physrevb.68.100503

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