The effect of oxygen vacancy on magnetism of geometrically frustrated triangular lattice CuFeO2: Ab initio study

The geometric, magnetic and electronic structures of oxygen-deficient CuFeO₂ crystal have been studied with the GGA plus on-site repulsion U method. In CuFeO₂, oxygen vacancy has the influences on two aspects. One is the decrease of lattice parameters, another is the valence change of Fe and Cu ion induced by the change of ionic charge number. In addition, when the oxygen vacancy appear in CuFeO₂, the stability of collinear antiferromagnetic structure is enhanced. Furthermore, the electronic structure analysis suggest that there may be a powerful magnetoelectric coupling effect in oxygen-deficient CuFeO₂ crystal, since the crystal is a zero gap conductor in ferromagnetic state while having a small gap in antiferromagnetic state. This unique property exhibits potential application prospect for magnetoelectric current sensor.