Magnetoresistance in the normal state ofLa1.925Sr0.075CuO4+δ

The in-plane magnetoresistance of a high-quality single crystal of ${\mathrm{La}}_{1.925}$ ${\mathrm{Sr}}_{0.075}$ ${\mathrm{CuO}}_{4+\mathrm{\delta }}$ has been measured in both the high-symmetry transverse geometry and in the longitudinal geometry. In both orientations, the magnetoresistance is positive and shows conventional weak-field behavior. The measured longitudinal magnetoresistance, however, is found to be almost an order of magnitude smaller than the measured transverse magnetoresistance. A semiphenomenological theory based on anisotropic scattering from hypothesized hole-pocket Fermi surfaces is introduced, which can account for the latter positive effect, as well as for known Hall-effect measurements. We predict that, in the limit corresponding to perfectly coherent in-plane hole motion along (π,π), there should be no saturation effect in the high-symmetry transverse magnetoresistance.