Magnetic exchange bias and high-temperature giant dielectric response in SmCrO3 ceramics

Perovskite SmCrO3 ceramics had been synthesized by a solid state reaction method. X-ray diffraction shows that this compound possesses an orthorhombic structure with Pnma space group. Magnetic behavior was investigated by measurement of temperature dependent magnetization and isothermal hysteresis loops. The results reveal that there exists strong temperature dependence of magnetic ordering. The decrease of the magnetization below ~50 K is induced by the Sm3+ ordering, indicating the existence of spin reorientation. A negative exchange bias effect was analyzed in the situation of field cooling below 30 K. Moreover, high-temperature dielectric behavior and impedance spectrum were explored. This material was found to exhibit giant dielectric behavior. Impedance spectrum analysis indicates the ceramics to be electrically heterogeneous consisting of semiconducting grains and insulating grain boundaries. Both dielectric polarization and conduction follow thermally activated process with similar value of the activation energy, revealing close correlation.