Effect of diamagnetic cobalt on the exchange interactions in the layered lithium iron oxide

Abstract Layered LiFeO 2 is an antiferromagnet with a Neel temperature T N =20 K. Substituting Fe with diamagnetic Co 3+ surprisingly leads first (up to x =0.4), to an increase of the Weiss temperature θ and then above x =0.4 to a decrease due to a dilution effect. Magnetic properties are qualitatively interpreted within a mean field model, with ferromagnetic layers coupled antiferromagnetically. Estimation is given of the ferro- and antiferromagnetic interactions.