Magnetic-field-enhanced electron-electron scattering in the resistivity of copper

Our measurements of the electrical resistivity ${\rho }_d$(T) on high-quality copper whiskers reveal a $T^2$ variation at very low temperatures. With the taking into account of appreciable corrections for surface scattering, the coefficient for electron-electron scattering in bulk copper could be determined, A=Δρ/$T^2$=27 fΩ cm ${\mathrm{K}}^{\mathrm{-}2}$, in good agreement with calculations assuming an isotropic relaxation time τ(k→). For the first time, a strong enhancement of A by a longitudinal magnetic field is observed, which is related to an anisotropy of τ(k→). At 4 T we find A≃110 fΩ cm ${\mathrm{K}}^{\mathrm{-}2}$ independent of an induced dislocation density of about ${10}^9$ ${\mathrm{cm}}^{\mathrm{-}2}$. .AE