Low-Temperature Magnetoresistance Effect in the Hydrothermally Synthesized La0.98 Ca0.02MnO3-δ/γ-Mn2O3 Granular System

The low-temperature magnetoresistance (LTMR) in hydrothermally synthesized La 0.98 Ca 0.02 MnO 3- δ / γ -Mn 2O 3 granular system was investigated. As-prepared powders are amorphous except for a small amount of crystalline phase LaCO 3OH. After sintered at 1 073 K or above, La 0.98 Ca 0.02 MnO 3- δ perovskite and secondary phase γ -Mn 2O 3 coexist. A large LTMR of ～65% at 127 K and ～50% at 0 K in the sample with mean grain size of 23 nm was observed. The observation of a large magnetoresistance over a wide temperature interval could be of importance for useful applications.