Normal-state magnetoresistance of Sr₂RuO₄ single crystals

We have measured the normal-state magnetoresistance (MR) of superconducting Sr₂RuO₄ single crystals (T_c0 = 0.84 K) between 1.5 and 300 K in all magnetic fields up to 7.3 T. For in- and out-of-plane MR, Δρ_ab and Δρ_c, the current was applied in the ab plane and along the c axis, respectively. In both cases, the magnetic field was perpendicular to the applied current. We found that both Δρ_ab(H)/ρ_ab(0) and Δρ_c(H)/ρ_c(0) are positive at low temperatures and decrease in magnitude with increasing temperature, eventually changing their signs from positive to negative at a temperature T* ≈ 75 K. Further analysis indicates that, below T*, the magnetic field dependence of Δρ_ab(II)/ρ_ab(0) is different from that of Δρ_c(II)/ρ_c(0).