Transport and magnetic properties of nanocrystalline La2/3Srl/3MnO3 powders synthesized by a nitrate–citrate gel-combustion process

Abstract We present magnetic and transport properties of nanocrystalline La 2/3 Sr l/3 MnO 3 powders prepared following a novel gel-combustion method using citric acid as the fuel. Magnetization ( M ) and magnetoresistance (MR) loops as a function of the applied magnetic field show that the coercive magnetic field H c is significantly different to the field H c * for which the resistance is maximum. A power-law dependence of the MR with magnetization, MR∝M n , with n ⩾2.5 has been observed at low fields between 5 and 200 K. The results are discussed in terms of spin-polarized tunneling models with a distribution of particle size in our sample.