Magnetic field dependence of threshold electric field for magnetoelectric switching of exchange-bias polarity

We report the magnetic field dependence of the threshold electric field E_th for the magnetoelectric switching of the perpendicular exchange bias in Pt/Co/Au/Cr₂O₃/Pt stacked films using a reversible isothermal electric tuning approach. The E_th values for the positive-to-negative and negative-to-positive switching are different because of the unidirectional nature of the interfacial exchange coupling. The E_th values are inversely proportional to the magnetic-field strength, and the quantitative analysis of this relationship suggests that the switching is driven by the nucleation and growth of the antiferromagnetic domain. We also find that the magnetic-field dependence of E_th exhibits an offset electric field that might be related to the uncompensated antiferromagnetic moments located mainly at the interface.