Observation of spin glass ordering and Griffiths-like phase in polycrystalline Sm0.75Sr0.25CoO3 nanoparticles

In this present work, polycrystalline Sm 0.75 Sr 0.25 CoO 3 nanoparticles are synthesized by sol–gel combustion route and their structural and magnetic properties are reported. The thermal study of as-prepared powder indicates that Sm 0.75 Sr 0.25 CoO 3 materializes at about 950 °C. The X-ray diffraction pattern of Sm 0.75 Sr 0.25 CoO 3 confirms the single-phase perovskite structure with orthorhombic symmetry and average crystallite size is found to be 17 nm. Field emission scanning electron microscope images of Sm 0.75 Sr 0.25 CoO 3 show the spherical particles. The temperature dependence of zero field cooled and field cooled magnetization curves are measured under the applied magnetic fields such as H = 100 Oe, 1000 Oe and 10,000 Oe show magnetic irreversibility for the present sample. The present sample exhibits a paramagnetic to ferromagnetic transition with a Curie temperature ( T C ) is equal to 95 K at 100 Oe. Field dependence magnetization shows magnetic hysteresis at low temperature with a coercive field of 0.38 T and linear dependence at high temperature corresponds to the paramagnetic region. The temperature dependence of inverse susceptibility above T C confirms the presence of Griffiths phase which proves the existence of ferromagnetic clusters in the paramagnetic region. The Arrott plot indicates that the second order phase transition is taking place. AC susceptibility of Sm 0.75 Sr 0.25 CoO 3 certifies the spin glass nature of the present sample. These findings suggest promising applications of Sm 0.75 Sr 0.25 CoO 3 materials in colossal magneto resistance devices.