Exchange bias effect in polycrystalline NiO/NiMn2O4 composite

Calcination of aqueous solutions formed by different molar ratios between the nickel and manganese chlorides led to the formation of antiferromagnetic NiO/ferrimagnetic NiMn2O4 oxide composites, as determined by X-ray powder diffraction technique and Rietveld refinement. Low temperature zero field cooled and field cooled magnetic hysteresis cycles show an exchange bias effect, presumably due to interaction at the interfaces between the antiferromagnetic and ferrimagnetic materials.