Anomalous Resistivity ofNb3Sn

Abstract

The resistivity of several specimens of niobium stannide has been measured over the range 18-850\ifmmode^\circ\else\textdegree\fi{}K. The resistivity rises rapidly up to 200\ifmmode^\circ\else\textdegree\fi{}K and then approaches a linear variation with a considerably smaller slope. Over the entire range the resistivity can be fit to better than 1% by the form $\ensuremath{\rho}(T)={\ensuremath{\rho}}_{0}+{\ensuremath{\rho}}_{1}T+{\ensuremath{\rho}}_{2}\mathrm{exp}(\ensuremath{-}\frac{{T}_{0}}{T})$ where ${\ensuremath{\rho}}_{0}\ensuremath{\approx}1\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}5}$\ensuremath{\Omega}-cm, ${\ensuremath{\rho}}_{1}=4.66\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}8}$\ensuremath{\Omega}-cm/\ifmmode^\circ\else\textdegree\fi{}K, ${\ensuremath{\rho}}_{2}=7.47\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}5}$\ensuremath{\Omega}-cm, and ${T}_{0}=85\ifmmode^\circ\else\textdegree\fi{}$K. Hall measurements made at 27, 77, and 300\ifmmode^\circ\else\textdegree\fi{}K, if interpreted on a one-band model, indicate a constant hole density of 1.77\ifmmode\times\else\texttimes\fi{}${10}^{22}$/cc, and an effective valence of 0.27/atom. The anomalous resistivity can not be explained on the basis of present models of the resistivity of transition metals, although the constancy of the Hall constant implies that the scattering probability rather than the effective number of carriers is changing with temperature. The relevance of the present results to recent models of the electronic structure of ${\mathrm{Nb}}_{3}$Sn is discussed.