  We report the results of Hall coefficient R_H and magnetoresistance (MR)
measurements on single crystalline samples of Sr3Ru2O7 grown by the floating
zone method. R_H was found to be positive over the entire temperature range
studied (0.3 - 300K). Its temperature (T) dependence follows closely that of
the magnetic susceptibility, including a maximum at a characteristic
temperature T=17 K. We show that R_H can be decomposed into normal and
anomalous parts as in the case of skew scattering in heavy-fermion compounds
and ferromagnetic metals. This, together with the observation that the
longitudinal MR is greater than the transverse MR at the same magnetic field
and temperature, suggests that magnetic fluctuations dominate the electrical
transport properties in Sr3Ru2O7. We found a crossover in the sign of the MR at
T*, from positive to negative as the temperature increased, for both the
transverse and the longitudinal configurations. In addition, a non-monotonic
behavior in the field dependence of the MR was found at low temperatures. These
observations suggest that the magnetic correlations in Sr3Ru2O7 at ambient
pressure undergo a qualitative change as the temperature is lowered. Above T*,
they are dominated by ferromagnetic instability. However, below T*, the system
crosses over to a different behavior, controlled possibly by a canted
antiferromagnetic instability.
