EXPERIMENTAL STUDY OF THE RESISTIVITY TENSOR IN Bi2Sr2CaCu2O8+x CRYSTALS BY MEANS OF MULTI-TERMINAL MEASUREMENTS

Abstract

We present measurements of the in-plane (ρab) and out-of-plane (ρc) resistivity in BSCCO single crystals. The resistivities are measured simultaneously on the same sample by means of a multi-terminal technique. Results are presented in the normal state and in the superconducting state, both in presence and in absence of an applied magnetic field. We underline the main differences with standard four probe measurements, showing in which cases the new method is strictly needed to avoid erroneous results. The technique is also able to test the locality of the dynamic: we present an accurate experimental analysis of the temperature and magnetic field ranges where the dynamic is local or non local. We finally show that above Tc this method gives results reliable enough to allow for a detailed study of the excess conductivity. We find that the data do not follow simple Aslamazov-Larkin laws in temperature ranges wider 1K, and that an accurate description of the data over a wide temperature range must include the effects of a short-wavelength cutoff in the fluctuational spectrum.