Magneto-optical and Nuclear Magnetic Resonance Studies of RbNiF3

The Faraday rotation (FR), magnetic circular dichroism (MCD), magnetic linear dichroism (MLD) and nuclear magnetic resonance (NMR) have been studied in the transparent ferrimagnet RbNiF3 (TC = 139°K). It was found that MCD and asymmetric anomalous dispersion of FR may be explained by the exchange splitting of electronic states of Ni2+ ions below TC. The structure and the temperature dependence of MCD of A23→1Ea transition confirms the model of magnetic structure with two unequivalent antiferromagnetically aligned sublattices. For the first time on the basis of NMR results the existence of two oppositely directed sublattices at temperatures about 100° above TC was observed in external magnetic field. The magnetization of one sublattice changes sign at T≃270°K.