Wide range magnetoresistance and high temperature coefficient of resistance in La0.7Sr0.3-xAgxMnO3 system

We report observation of composition and process parameter dependant wide range magnetoresistance and high temperature coefficient of resistance in La0.7Sr0.3-xAgxMnO3 (0 <= x <= 0.3) system. The polycrystalline samples synthesized through solid state reaction method exhibited rhombohedral structure with systematic change in lattice parameters. The samples with x <= 0.2 showed metallic behavior below room temperature. A broad metal-insulator transition is observed for x = 0.3, which becomes sharp for the samples sintered at high temperature. The broad transition resulted in magnetoresistance (MR) value around 35% over a wide temperature range whereas the sharp transition results in MR value as high as 85%. The temperature coefficient of resistance value of 11% is seen as a consequence of sharp transition. The magnetic transition was sharp for the samples sintered at high temperature.