Structure and ferromagnetism in vanadium-doped LiNbO3

Doping into LiNbO3 (LN) and studying its magnetism might provide an alternative way for fabricating diluted magnetic compounds with potential application in the field of spintronics. Room-temperature ferromagnetic V-doped LN with V contents of 1-3 at. % was prepared by ion-beam implantation. The samples exhibit a maximum atomic magnetic moment of 3.82 mu(B)/V at a V doping concentration of 2 at. %. Structural characterization and first principle calculation suggest that the magnetism most likely arises from the oxygen vacancy around the V dopant. X-ray absorption near-edge spectroscopy reveals that the V atom principally substituted for the Nb atom in the LN lattice and that the V is octahedrally coordinated but with a large distortion. It also showed that oxygen vacancies are present in the third shell of the doped V atoms. With the aid of first-principle calculations, we constructed the electronic structure of this system and demonstrated that the 0 vacancies play an important role in modulating the magnetism. These 0 vacancies can release the magnetic moment of the V dopant and enhance spin coupling over a long range. Two 0 vacancies are estimated to have an atomic magnetic moment of 4 mu(B), which is consistent with the results of magnetic measurements. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4745053]