Magnetic properties of nanosized Sr2CrReO6 powders prepared by a combustion synthesis process

Double perovskite, Sr2CrReO6, nanoparticles in the size range 10–25 nm have been prepared by a combustion method. Its coercivity (Hc) at 5 and 300 K are determined to be 16.1 and 6.5 kOe, respectively. Using the law of approach to saturation, the obtained saturation magnetization σs (5 K) and σs (300 K) are 0.41 and 0.32 μB per formula unit (f.u.), respectively. The values of saturation magnetization are lower than the expected value 1 μB/f.u. considering the antiferromagnetic coupling between Cr3+ (3d3, S = 3 / 2) and Re5+ (5d2, S = 1). At the same time high field irreversibility in M(H) curves and zero field cooled–field cooled (ZFC–FC) processes has also been found. A field-cooled (FC) hysteresis loop shift decreases with increasing temperature and vanishes near 350 K. It is suggested that the observed reduction of σs and shifted hysteresis loops are caused by the exchange interaction between the ferromagnetic core of the Sr2CrReO6 nanoparticles and its surface layer with disordered spins.