Room temperature ferromagnetism of nonmagnetic element Ca-doped LiNbO3 films

The nonmagnetic element Ca-doped LiNbO3 films were prepared on Si （111） substrates by radio frequency （RF） mag- netron sputtering technique. X-ray diffraction （XRD） and X-ray photoelectron spectroscopy （XPS） indicate that the Ca atoms enter the LiNbO_3 lattice in the form of Ca^2＋ ions. Superconducting quantum interference device （SQUID） resuits show that the Ca-doped LiNbO_3 films have room-temperature ferromagnetism and a maximum saturation magnetization of 4800 A/m at the 3% of Ca atom doping concentration. The room temperature ferromagnetism of the Ca-doped LiNbO_3 films can be attributed to the occurrence of vacancies due to Ca doping and is the intrinsic property.