Anomalous temperature dependence of the resistivity of some intermetallic compounds

The resistivity rho of some intermetallic compounds such as Nb ₃Sn, V₃Si, UAl₂, etc. has an anomaly at a temperature T₀ near 100K. The resistivity rises steeply with T below T₀ and less steeply above it. Here the authors account for this anomalous temperature dependence using the 'classical' s-d model. Below T ₀ the s-like and d-like states are hybridised by a small electronic matrix element J_sd (J_sd approximately=10-50 meV) and the electron-phonon coupling constant lambda is large. Above T₀ the electron-phonon scattering rate h(cross)/ tau exceeds J_sd, and the s-like and d-like states are decoupled. The electrical conductivity is then due mainly to the s-like states which possess a smaller electron-phonon coupling constant lambda , giving rise to a smaller value of d rho /dT. The anomaly occurs when the mean free path l is about an order of magnitude larger than the interatomic spacing d.