Anomalous Hall effect in an antiferromagnetic CeGaSi single crystal

We report a detailed investigation of the magnetic and electrical transport properties in an antiferromagnetic CeGaSi crystal. It orders ferromagnetically within the $ab$ plane and antiferromagnetically along the $c$ axis below ${T}_{N}\phantom{\rule{0.28em}{0ex}}(\ensuremath{\sim}12\phantom{\rule{0.16em}{0ex}}\mathrm{K})$. The magnetotransport in CeGaSi shows anisotropy with the emergence of negative magnetoresistance (MR) within the $ab$ plane and along the $c$ axis. At low temperatures, the initially negative MR within the $ab$ plane changes sign and becomes positive with $B$ further increasing and approaching saturation. When the field is applied along the $c$ axis, the MR remains negative, as a result of the suppression of spin scattering in the antiferromagnetic state. Interestingly, different Hall responses are also demonstrated. A prominent anomalous Hall effect (AHE) is observed with $B\ensuremath{\parallel}ab$ in CeGaSi with a maximum value of anomalous Hall conductivity $|{\ensuremath{\sigma}}_{xz}^{A}|\ensuremath{\sim}128\phantom{\rule{4pt}{0ex}}{\mathrm{\ensuremath{\Omega}}}^{\ensuremath{-}1}\phantom{\rule{0.16em}{0ex}}{\mathrm{cm}}^{\ensuremath{-}1}$. The scaling behaviors of anomalous Hall resistivity and conductivity indicate the skew scattering as the dominant mechanism of AHE in CeGaSi. However, the AHE is absent and only the normal Hall effect is observed with $B\ensuremath{\parallel}c$. These fascinating findings in MR and Hall measurements not only establish CeGaSi as a new platform to study AHE, but also deepen our understanding on the interesting physical phenomena associated with magnetic properties.