Room-temperature ferromagnetism in Li-doped p-type luminescent ZnO nanorods

We have observed ferromagnetism in Li-doped ZnO nanorods with Curie temperature up to 554 K. Li forms shallow acceptor states in substitutional zinc sites giving rise to p-type conductivity. An explicit correlation emerges between increase in hole concentration with decrease in magnetization and Curie temperature in ZnO:Li. Occurrence of ferromagnetism at room temperature has been established with observed magnetic domain formation in ZnO:Li pellets in magnetic force microscopy and prominent ferromagnetic resonance signal in electron paramagnetic resonance spectrum. Magnetic ZnO:Li nanorods are luminescent, showing strong near UV emission. Substitutional Li atoms can induce local moments on neighboring oxygen atoms, which when considered in a correlated model for oxygen orbitals with random potentials introduced by dopant atom could explain the observed ferromagnetism and high Curie temperature in ZnO:Li nanorods.