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

Abstract: We report a comprehensive investigation of CeGaSi single crystals, including magnetic, thermodynamic, electronic, and magnetotransport properties. The powder x-ray diffraction refinement revealed that CeGaSi crystallizes in LaPtSi-type tetragonal structure with space group I41md. The electrical resistivity data show a metallic nature with a sharp drop occurring around T_m = 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 point charge model, suggesting that the six degenerate ground states of Ce3+ (J = 5/2) ion split into three doublets with an overall splitting energy = 288 K. The maximum negative magnetoresistance in CeGaSi for both B\parallel c and B\parallel ab field-direction is observed near T_m, it is attributed to the suppression of spin-disorder scattering by the magnetic field. The Hall resistivity data for B \parallel c and B\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.