The large magnetic anisotropy in the layered ferromagnet ${\mathrm{Fe}}_{1∕4}\mathrm{Ta}{\mathrm{S}}_2$ leads to very sharp reversals of the magnetization $\mathbf{M}$ at the coercive field. We have exploited this feature to measure the anomalous Hall effect (AHE), focusing on the AHE conductivity ${\sigma }_{xy}^A$ in the inelastic regime. At low temperature $T$ $(5–50\mathrm{K})$, ${\sigma }_{xy}^A$ is $T$ independent, consistent with the Berry-phase/Karplus-Luttinger theory. Above $50\mathrm{K}$, we extract an inelastic AHE conductivity ${\sigma }_{xy}^{\mathit{in}}$ that scales as the square of $\Delta \rho$ (the $T$ dependent part of the resistivity $\rho$). The term ${\sigma }_{xy}^{\mathit{in}}$ clarifies the $T$ dependence and sign reversal of the AHE coefficient $R_s\left(T\right)$. We discuss the possible ubiquity of ${\sigma }_{xy}^{\mathit{in}}$ in ferromagnets and ideas for interpreting its scaling with ${\left(\Delta \rho \right)}^2$. Measurements of the magnetoresistance (MR) reveal a rich pattern of behavior vs $T$ and field-tilt angle. We show that the two mechanisms, the anisotropic MR effect and field suppression of magnons, account for the intricate MR behavior, including the bow-tie features caused by the sharp reversals in $\mathbf{M}$.

• Received 8 August 2007

DOI:https://doi.org/10.1103/PhysRevB.77.014433