Cr doping in the La_1.2Sr_1.8Mn₂O₇system

Abstract

The effect of doping Cr in the Mn site of the La1.2Sr1.8Mn2O7 system has been studied. Addition of Cr modifies the transport and magnetic properties of the parent phase. With increasing Cr, the insulator-metal transition observed in the parent phase is suppressed and insulating behaviour is induced. In the range of doping studied (25%), the compositions show ferromagnetic behaviour with the Curie temperature decreasing with increasing Cr. The unit cell volume also shows a decrease. However, the magnetoresistance ratio is not significantly affected. We compare these results with an earlier study of doping Cr in the three-dimensional LaMnO3 structure, where it was seen that the ferromagnetic and magnetoresistance characteristics are sensitive to Cr doping. The results of the present study suggest that the layered manganates are more accommodative to doping compared to the three-dimensional perovskites.