NONLINEAR TEMPERATURE-DEPENDENCE OF RESISTIVITY IN BI2SR2CUOY CRYSTALS

We have measured the ab-plane resistivity on a number of Bi2Sr2CuOy cr ystals from 4.2 K to 300 K. The as-grown crystals usually exhibit a mi nimum in their normal-state resistivity. The low-temperature electroni c transport can be described by a hopping conduction. As the crystals were annealed in the ambient flowing oxygen, they could become metalli c over the whole temperature range. A nonlinear temperature-dependent resistivity was observed and found to be sample dependent. Some rho(T) curves can be fitted to a power law with the exponent slightly greate r than 1, while others appear with a Bloch-Gruneisen-like shape. A dis cussion of the experimental results is presented.