Ordered double-perovskite Ca2FeMoO6 compounds with nanometer-scale grains:structure, magnetism, and intergrain tunneling magnetoresistance

Polycrystalline ordered double-perovskite Ca2FeMoO6 bulk samples with nanom eter-scale grain size have been synthesized using a sol-gel method. A large magnetoresistance (MR) of 7.6% at a low magnetic field of 0.5 T and room t emperature is obtained. The result of ac susceptibility shows that the samp le has two magnetic transitions at T-C1 = 374.6 K and T-C2 = 336.3 K, which may correspond to the orthorhombic structure and the monoclinic structure phase, respectively. Due to the large MR at room temperature and well ferro magnetic conductivity of Ca2FeMoO6, it may be a desirable material for prac tical applications in future. (C) 2001 Elsevier Science B.V. All rights res erved.