Synthesis and magnetic properties of DyMnO3 nanoparticles in mesoporous silica

We synthesized nanoparticles of the perovskite manganite DyMnO3 in pores of mesoporous silica SBA-15 and investigated their magnetic properties. X-ray diffraction patterns of the nanoparticles indicated successful synthesis of the DyMnO3 nanoparticles with a particle size of about 10 nm in the pores of SBA-15. The temperature dependence of the DC magnetic susceptibility for the DyMnO3 nanoparticles exhibited a pronounced magnetic irreversibility between the field-cooling and the zero-field-cooling susceptibility due to the blocking phenomena and indicated a change of the magnetic exchange interactions from those for the bulk crystal. The in-phase susceptibility χ′ and the out-of-phase susceptibility χ″ of the AC susceptibility for the nanoparticles exhibited a peak at the blocking temperature, and that peak shifted toward higher temperature with increasing frequency. Magnetization curves for the nanoparticles were reproduced by using a Langevin function and exhibited a hysteresis loop at temperatures below the blocking temperature. Magnetic size effects and superparamagnetic behaviors were observed in the DyMnO3 nanoparticles.