Magnetoresistive behaviour of La 0.67(Ca 0.33− xPb x)MnO 3 nanopowders prepared at lower temperature

Abstract

We have been able to prepare ultrafine powders of pure and doped La 0.67Ca 0.33MnO 3 (LCMO) at a relatively lower temperature of 550°C using a simple, cost effective and versatile PVA-based chemical route. A maximum magnetoresistance (MR) ratio of −25% is obtained at 20 K in a magnetic field of 3 kOe. Magnetoresistive behaviour being retained in the nanopowders may have implications for enhancing data storage capacity. The semicondutor-to-metal transition temperature, T p, however, shifts towards the lower temperature as the particle size is reduced. To improve T p and near-room-temperature MR additives like NH 4NO 3 and citric acid have been used. In addition, Pb is substituted for Ca.