Improved eddy-current decay method for resistivity characterization

Eddy-current decay is a unique, nondestructive method for determining the low-temperature resistivity of large samples of pure metal. Furthermore, it is the only means available for measurement of the residual resistivity ratio (RRR), ρ(273 K)/ρ(4 K) of samples with shapes that do not lend themselves to conventional four-wire resistance measurement techniques. An improvement to an earlier implementation of the eddy-current decay method of resistivity characterization is presented. It involves modernizing the earlier apparatus by the use of a digitizing oscilloscope, commercial curve-fitting software, digital averaging techniques, and modern electronics. Data are shown for high-purity copper cylinders