We have investigated the extraordinary Hall effect of ${\text{Ba}}_{1-x}{\text{Sr}}_x{\text{RuO}}_3$ thin films with $x=1$ and 0.8. For $x=1$, the extraordinary Hall resistivity can be interpreted by the skew scattering mechanism in the paramagnetic region above about 160 K. In the ferromagnetic region above about 60 K, the extraordinary Hall coefficient $R_s$ can be expressed by the combination of the skew and the side-jump scattering mechanisms as $R_s=a\rho +b{\rho }^2$ using the electrical resistivity $\rho$, as usually observed in ordinary ferromagnetic metals. Below 60 K, the field dependence of the Hall resistivity ${\rho }_H$ at intermediate field region cannot be expressed as ${\rho }_H=R_{0}B+R_{s}M$, suggesting an additional term in the field dependence of the extraordinary Hall resistivity. $R_s$ below 60 K derived from the high field region does not follow the relation $R_s=a\rho +b{\rho }^2$, suggesting that the coefficients $a$ and $b$ of the skew and the side-jump scattering depends on temperature below 60 K. On the other hand in the sample with $x=0.8$, no anomalies were observed below 60 K both in temperature and field dependence. According to the structural analysis of the samples, we infer that the modulation of the Fermi surface due to the structural change plays an important roll on the anomaly of the temperature dependence of the extraordinary Hall effect for $x=1$.

• Received 18 August 2010

DOI:https://doi.org/10.1103/PhysRevB.82.174430