Ferromagnetism in Co doped CeO2: Observation of a giant magnetic moment with a high Curie temperature

We report room temperature ferromagnetism in single crystal Ce1−xCoxO2−δ (x⩽0.05) films deposited on a LaAlO3(001) substrate. Films were grown by a pulsed laser deposition technique and were thoroughly characterized using x-ray diffraction, high-resolution transmission electron microscopy coupled with electron energy loss spectroscopy and scanning transmission electron microscopy-Z contrast, x-ray photoelectron spectroscopy, optical transmission spectroscopy, and magnetic measurements. These films are transparent in the visible regime and exhibit a very high Curie temperature ∼740–875K with a giant magnetic moment. Our results indicate that the ferromagnetic property is intrinsic to the CeO2 system and is not a result of any secondary magnetic phase or cluster formation.