Effect of grain size on magnetoresistance in Ba2FeMoO6

Effect of grain size on magnetoresistance (MR) and electrical and magnetic properties of double perovskite Ba2FeMoO6 (BFMO) have been investigated. BF MO samples with different grain size have been prepared by the conventional solid state reaction followed by sintering in a stream of 5% H-2/Ar at 110 0 degreesC with various sintering times. The size of grain increases with i ncreasing of sintering time. Temperature dependent magnetization is the sam e for samples with different grain size. However, electrical resistivity rh o (T) and MR are affected by the grain size; the rho (T) and the MR value d ecrease with an increase in grain size. In spite of the different grain siz e, the rho (T) shows a metallic behavior below the ferromagnetic transition temperature. Low magnetic field applied to the sample considerably reduces the resistivity over the whole temperature. The magnitude of MR for the sa mple sintered for 5 h is as large as 31% and 7% with the magnetic field of 0.7 T at 12 and 300 K, respectively. (C) 2001 American Institute of Physics .