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

Polycrystalline ordered double-perovskite Ca2FeMoO6 bulk samples with nanometer-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 temperature is obtained. The result of ac susceptibility shows that the sample 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 ferromagnetic conductivity of Ca2FeMoO6, it may be a desirable material for practical applications in future. (C) 2001 Elsevier Science B.V. All rights reserved.