The pair-breaking critical current density of magnesium diboride

TL;DR

This study measures the pair-breaking critical current density of magnesium diboride across all temperatures using pulsed dc transport, confirming its consistency with Ginzburg-Landau theory and providing a key parameter for superconductor performance.

Contribution

The paper provides the first comprehensive measurement of the pair-breaking critical current density of magnesium diboride over its entire temperature range, validating theoretical models.

Findings

Projected j_{d}(0) ≈ 2 × 10^{7} A/cm^{2}

Measured j_{d}(T) aligns with Ginzburg-Landau theory

Resistive transition temperature shifts follow classic j dependence

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 \Delta T_{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/cm^{2}. The directly measured j_{d}(0), from current-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