Eleventh International Conference on Internal Friction and Ultrasonic Attenuation in Solids
J. Phys. IV France 06 (1996) C8-515-C8-518
Electron Mean Free Path Independence of the Glasslike Properties of Polycrystalline MetalsE. Gaganidze and P. Esquinazi
Dept. Superconductivity and Magnetism, University of Leipzig, Linnéstrasse 5, 04103 Leipzig, Germany
We have measured the sound velocity and attenuation of polycrystalline Cu, Al, Nb, Nb48Ti52, Pt, Pt70Rh30, Pt(1%W), Pd, Ta, NiCr alloy and amorphous PdSiCu at frequencies 0.1 kHz<v<20kHz and at temperatures 40mK<T<10K. All polycrystalline samples show acoustic properties which resemble those of dielectric glasses. Their electrical resistivity is in the range 10-10Ωm<ο<10-5Ωm with an estimated electron mean free path of 10-10m<l<;10-5m. Our results indicate no correlation between the tunneling system density of states or coupling constant and the electron mean free path, supporting earlier work on the absence of electron assisted relaxation rate. For polycrystalline metals we found that the ratio Tco/v1/3≈(0.006+/-0.002) K/Hz1/3 in agreement with dielectric glasses (Tco is the temperature at the sound velocity maximum).
© EDP Sciences 1996