A temperature-dependent switching of the exchange bias effect from negative to positive under a fixed intermediate cooling field.

An interfacial coupling origin of the exchange bias effect (EBE) is a novel phenomenon due to its technological and fundamental importance. We have carefully synthesized an FeO@NiO (FO@N) core@shell (CS) nanostructure using a co-precipitation method, and the CS nanostructure formation was evident from the HRTEM analysis. The magnetic measurement study endorses unique characteristics on the temperature-dependent EBE switching from negative to the positive axis under a fixed cooling field. To the best of our knowledge, this unique characteristic behavior at a fixed cooling field has not been reported, particularly for the ferro/ferrimagnetic@antiferromagnetic FiM@AFM CS nanostructure. The switching is attributed to a formation of ferromagnetic (negative) or antiferromagnetic (positive) coupling arrangement at the magnetically disordered interface of two materials.