Ring exchange in transition metal oxides: a new manifestation in Li2CuO2?

Magnetic edge-sharing chain compound Li2CuO2 is considered. Previously, noted contradiction between the standard model calculations and the experimental estimates of the intrachain spin coupling is resolved, at least qualitatively. The proposed scenario is based on the ring exchange mechanism explaining a ferromagnetic superexchange coupling between distant Cu spins. (C) 2002 Elsevier Science B.V. All rights reserved