Electric-field tuning of the metal-insulator transition in ultrathin films of LaNiO3

Epitaxial ultrathin films of the metallic perovskite LaNiO3 were grown on (001) SrTiO3 substrates using off-axis rf magnetron sputtering. The film structure was characterized and their electrical properties investigated. Films thinner than 8 unit cells display a metal-insulator transition at a thickness dependent characteristic temperature. Hall measurements revealed p-type conduction, which was confirmed by electric field-effect experiments. Large changes in the transport properties and the metal-insulator transition temperature were observed for the thinnest LaNiO3 films as the carrier density was electrostatically tuned.