Matthiessen's rule in $\mathrm{Mg}{\mathrm{B}}_{2}$: Resistivity and ${T}_{c}$ as a function of point defect concentration

Matthiessen’s rule in $Mg B_{2}$ : Resistivity and $T_{c}$ as a function of point defect concentration

B. Sipos, N. Barisic, R. Gaal, L. Forró, J. Karpinski, and F. Rullier-Albenque

Phys. Rev. B 76, 132504 – Published 4 October 2007

Abstract

We present the results of a systematic study of the temperature-dependent resistivity and of $T_{c}$ of a single crystal $Mg B_{2}$ sample as a function of point defect concentration. We have found linear, albeit weak, correlation between the decreasing superconducting critical temperature and the residual resistivity and no variation of the slope of the $ρ (T)$ curve at high temperature. These findings reinforce the already existing picture of $s$ -wave pairing for the superconductivity. The interband scattering is low despite increasing disorder. Somewhat surprisingly, Matthiessen’s rule is followed even in this two-band metal.