Magnetic and transport properties of nanocrystalline double perovskite Sm2CoMnO6

Double perovskite Sm2CoMnO6 nanoparticles of diameter around 200 nm were synthesized by a sol-gel technique. They showed ferromagnetic transition with a Curie temperature of 139K. The saturation magnetization per formula unit (3.74 μB/f.u.) as derived from magnetization-field data at 2K was smaller than the theoretical value 6 μB/f.u.. This was ascribed to the presence of antisite disorder. The resistivity was found to be controlled by a variable range hopping mechanism. The material exhibited negative magnetoresistance with a maximum value of 3% at 170K for an applied field of 5T. This was ascribed to spin-polarized electron hopping between magnetic domains coupled by an antiferromagnetic interaction.