Observation of spin glass ordering and Griffiths-like phase in polycrystalline Sm0.75Sr0.25CoO3 nanoparticles
In this present work, polycrystalline Sm0.75Sr0.25CoO3 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 Sm0.75Sr0.25CoO3 materializes at about 950 °C. The X-ray diffraction pattern of Sm0.75Sr0.25CoO3 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 Sm0.75Sr0.25CoO3 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 (TC) 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 TC 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 Sm0.75Sr0.25CoO3 certifies the spin glass nature of the present sample. These findings suggest promising applications of Sm0.75Sr0.25CoO3 materials in colossal magneto resistance devices.
The authors thank the Central Instrumentation Facility, Pondicherry University for providing experimental facilities and PSG COE INDUTECH for FESEM facility. B. Sathyamoorthy thanks UGC for the financial assistance in the form of Basic Science Research fellowship (File No. PU/PHYS/GC/UGC-BSR/2014-15/724).
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