Room temperature ferromagnetism and ferroelectricity in cobalt-doped LiNbO3 film

Abstract

( 5 at. % ) cobalt-doped LiNbO3 (Co:LN) films were prepared by combinatorial laser molecular-beam epitaxy on Si (100). The Co:LN films with Co2+ replacing Nb exhibit room temperature ferromagnetism of 1.2μB∕Co and Curie temperature of ∼540K. Through a Ag∕Co:LN∕Si metal-ferroelectric-semiconductor field effect transistor configuration, ferroelectric measurements show that the films display hysteresis loops at 300K and ferroelectric transition temperature of ∼610K. The hysteresis and the asymmetry in capacitance-voltage and leakage-voltage curves are ascribed to trapping/detrapping process of charges at the Co:LN/Si interface. The coexistence of room temperature ferromagnetism and ferroelectricity makes Co:LN a promising single-phase multiferroic.