Low-temperature magnetic behavior of the rare-earth cobaltites GdCoO3 and SmCoO3

The temperature and magnetic field dependences of the static magnetization of the polycrystalline rare-earth cobaltites GdCoO₃ and SmCoO₃ have been measured. It is shown that, below room temperature, the magnetization of both compounds derives primarily from the rare-earth ion paramagnetism. The GdCoO₃ and SmCoO₃ compounds have been found to differ substantially in magnetic behavior, which can be traced to differences in their electronic shell structures. The magnetic behavior of GdCoO₃ is close to that of an array of free Gd³⁺ ions, whereas in SmCoO₃ the deviation from the free-ion properties is very large because of the Sm³⁺ ground state being crystal-field split. Van Vleck magnetic susceptibility measurements of SmCoO₃ suggest that the splitting is ～10 K.