Frequency-Dependent Electrical Conductivity of Dilute Magnetic Alloys

The frequency-dependent electrical conductivity of dilute alloys is expressed in terms of the impurity scattering t -matrix which is a function of temperature. The formula is applied to a few model examples for dilute magnetic alloys in which the imaginary part of the t -matrix has a sharp peak at the Fermi level, owing to the scattering by local spin fluctuations of magnetic impurities. The results show significant deviations from the Drude formula; the real part of the complex conductivity can have a peak at a finite frequency.