Bulk CeCo2 is characterized as a Pauli paramagnet, both Ce and Co are essentially nonmagnetic. The data of χ(T) show that CeCo2 nanoparticles exhibit extremely complex magnetic properties. Two magnetic phases, a major paramagnetic component and a minor ferromagnetic component, were detected in CeCo2 nanoparticles. A superparamagnetic behavior was shown at T>200 K and a low-temperature spin-glass-like behavior was observed at T=10–30 K. Such magnetic changes were attributed to the size effects in nanoparticles.
Journal of Magnetism and Magnetic Materials 239(1-3), pp.524-526