Crystalline electric field and large anomalous Hall effect in the candidate topological material CeGaSi

We report a comprehensive investigation of CeGaSi single crystals, including magnetic, thermodynamic, electronic, and magnetotransport properties. The powder x-ray diffraction refinement reveals that CeGaSi crystallizes in LaPtSi-type tetragonal structure with space group $I{4}_{1}md$. The electrical resistivity data show a metallic nature with a sharp drop occurring around ${T}_{m}\ensuremath{\sim}$ 11 K, revealing a magnetic phase transition, which is confirmed by magnetic susceptibility and heat capacity data. The magnetic susceptibility, magnetization, and heat capacity data are analyzed through the crystalline electric field based on the point charge model, suggesting that the six degenerate ground states of ${\mathrm{Ce}}^{3+}$ ($J=5/2$) ions split into three doublets with an overall splitting energy $\ensuremath{\sim}288$ K. The maximum negative magnetoresistance in CeGaSi for both $B\ensuremath{\parallel}c$ and $B\ensuremath{\parallel}ab$ field directions is observed near ${T}_{m}$, attributed to the suppression of spin-disorder scattering by the magnetic field. The Hall resistivity data for $B\ensuremath{\parallel}c$ and $B\ensuremath{\parallel}ab$ show anomalous Hall signal. Our scaling analysis suggests that anomalous Hall effect in CeGaSi is dominated by the skew scattering mechanism. In addition, first-principles calculations identify CeGaSi as a nodal-line metal.