The pair-breaking critical current density of magnesium diboride

Abstract

The pair-breaking critical current density j_{d} of magnesium diboride was determined over its entire temperature range by a pulsed dc transport measurement. At fixed low values of current density j, the resistive transition temperature Tc shifts in the classic ΔT_{C}(j)/T_{C}(0) \propto -[j/j_{d}(0)]^{2/3} manner, with a projected j_{d}(0) \approx 2 \times 10^{7}$A/c{m}^2.Thedirectlymeasured{j}_d(0),fromcurrent-voltage($I$-$V$)curves at different fixed temperatures, has a similar value and the overall temperature dependence j_{d}(T) and magnitude are consistent with Ginzburg-Landau theory. Keywords: pair, breaking, depairing, superconductor, superconductivity, flux, fluxon, vortex, mgb2

arXiv commentSubmitted to Phys. Rev. Lett. Related preprints/reprints by our group can be found on http://www.physics.sc.edu/kunchur

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• Theory of the critical current in two-band superconductors with application to MgB2
• Transverse voltage in zero external magnetic fields, its scaling and violation of the time reversal symmetry in MgB2
• Critical flux pinning and enhanced upper-critical-field in magnesium diboride films
• Roles of intrinsic anisotropy and pi-band pairbreaking effects on critical currents in tilted c-axis MgB2 films probed by magneto-optical and transport measurements
• Fate of global superconductivity in arrays of long SNS junctions
• Peak effect in a superconductor/normal metal strip being in vortex-free state
• Dissipative-regime measurements as a tool for confirming and characterizing near-room-temperature superconductivity