Multiple magnetic transitions in single-crystal Gd5Rh4Ge10

Compounds belonging to the R 5 Ir 4 Si 1 0 family exhibit a variety of ground states depending on the nature of the rare-earth element R. In this work, we report resistivity, magnetization, and heat-capacity studies on a single crystal of Gd 5 Rh 4 Ge 1 0 . Unusual multiple magnetic transitions are observed in Gd 5 Rh 4 Ge 1 0 (where there is no crystal-field contribution). It appears that one of the four-fold transitions which occurs at the highest temperature is a second-order (continuous) phase transition while the other three probably involving moment reorientations and noncollinear amplitude modulations. In general, the basic cause of the magnetic orderings is due to anisotropic indirect exchange interaction (Ruderman-Kittel-Kasuya-Yasida type) coupled with multiple site occupancy of the Gd atoms.