On the T2dependence of surface-induced deviations from Mathiessen's rule in copper single crystals

Abstract

The effect of the sample thickness d (7 mu m<or approximately=d<or approximately=142 mu m) on the electrical resistivity rho (d,T) of single-crystal copper whiskers with residual electron mean free path le=242 mu m has been studied in the temperature range 4.2-40K. The observed deviations from Matthiessen's rule in the temperature-dependent part of the resistivity, Delta s(d,T) Delta = rho (d,T)- Delta rho ( infinity ,T), reveal a T2 variation in a narrow temperature range, 10-20K. The experimental data are in quantitative agreement with the size-effect calculations of Sambles et al. (1984) if the surface roughness is regarded as an adjustable parameter which decreases with increasing sample thickness.