INPLANE AND OUT-OF-PLANE MAGNETORESISTANCE IN LA2-XSRXCUO4 SINGLE-CRYSTALS

The magnetoresistance of La2-xSrxCuO4 single crystals has been studied extensively over a wide composition range (0.07 less than or equal to x less than or equal to 0.28) using current parallel (in plane) and p erpendicular (out of plane) to the CuO2 plane. In the underdoped super conducting phase (x similar to 0.10), the in-plane magnetoconductivity above T-c is well described as fluctuation conductivity but only with the Aslamasov-Larkin term. The negligibly small Maki-Thompson contrib ution is suggestive of anisotropic Cooper pairing. We find a pronounce d negative and isotropic out-of-plane magnetoresistance at low tempera tures in this composition range. In the optimally doped to the overdop ed superconducting phases (0.15 less than or equal to x less than or e qual to 0.20), a substantial normal-state component is observed in the in-plane magnetoresistance. The classical Kohler's rule appears to br eak down for the normal-state magnetoresistance, which supports the in volvement of two distinct scattering rates tau(tr) and tau(H). In the out-of-plane magnetoresistance; we find an unconventional scaling Delt a rho(c)/rho(c) proportional to(H/rho alpha)(2) for H perpendicular to J and (H/T)(2) for H parallel to J. In contrast to these anomalous be haviors, we find that Kohler's rule holds for both the in-plane and th e out-of-plane transverse magnetoresistance in the overdoped normal me tal region, implying a conventional anisotropic three-dimensional tran sport. These findings provide further evidence for the unconventional normal-state transport in the samples which exhibit high-T-c supercond uctivity.