Magnetic and electrical transport properties in GdAlSi and SmAlGe

We conduct a detailed examination of the magnetic and electrical transport properties in GdAlSi and SmAlGe crystals, which possess a LaPtSi-type structure (space group I4₁md). The magnetic susceptibility data unambiguously reveal magnetic ordering below a characteristic transition temperature (T_N). For GdAlSi, a hysteresis loop is observed in the magnetization and magnetoresistance curves within the ab plane when the magnetic field is applied below T_N, which is around 32 K. Notable specific heat anomalies are detected at 32 K for GdAlSi and 6 K for SmAlGe, confirming the occurrence of magnetic transitions. In addition, the extracted magnetic entropy at high temperatures is consistent with the theoretical value of Rln(2J + 1) for J = 7/2 in Gd³⁺ and J = 5/2 in Sm³⁺, respectively. SmAlGe also exhibits Schottky-like specific heat contributions. Additionally, both GdAlSi and SmAlGe exhibit positive magnetoresistance and a normal Hall effect.