In this study, the pulse-voltage-driven dynamical switching of perpendicular exchange bias in a Pt/Co/Au/Cr2O3/Pt thin film observed at pulse amplitudes exceeding the DC switching threshold is investigated. The switching time decreases with increasing pulse amplitude, reaching values below 10 ns at an amplitude two times higher than the above threshold. Conversely, several hundreds of nanoseconds is required for switching at amplitudes close to the threshold, suggesting that the switching mechanism is dominated by the motion of magnetic domains of the antiferromagnetic layer.

This study investigates the influence of Pt and Au spacer layers on the perpendicular exchange bias field and coercivity of Pt/Co/(Pt or Au)/Cr 2 O 3 /Pt films. When using a Pt-spacer, the perpendicular exchange bias was highly degraded to less than 0.1 erg/cm 2 , which was about half that of the Auspacer system. The Au spacer also suppressed the enhancement in coercivity that usually occurs at around room temperature when using Pt. It is suggested that this difference in exchange bias field is due to in-plane interfacial magnetic anisotropy at the Pt/Cr 2 O 3 interface, which cants the interfacial Cr spin from the surface normal and results in degradation in the perpendicular exchange bias.

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/Cr 2 O 3 /Pt stacked films using a reversible isothermal electric tuning approach. The E th values for the positive-to-negative and negative-topositive 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.

Energy condition for isothermal reversible magnetoelectric switching of exchange bias was investigated using Pt/Co/Au/Cr 2 O 3 /Pt stacked films with different thicknesses of the antiferromagnetic layer (t AFM ). We discussed the effective magnetic anisotropy energy of the antiferromagnetic layer (K eff AFM ), the interface exchange coupling energy (J INT ), and the offset electric field (E 0 ). The dependence of K eff AFM on t AFM suggested that the magnetic domain wall motion significantly influenced the switching of the electric-field-induced magnetization similar to an ordinal ferromagnet. Below 0.025 mJ/m 2 , J INT was equal to the exchange anisotropy energy (J K ), and above 0.025 mJ/m 2 , J INT exceeded J K , suggesting that J K is restricted by the magnetic domain wall energy. The dependence of E 0 on t AFM revealed that E 0 mainly arose from the interfacial uncompensated antiferromagnetic moment. The obtained results suggest that the energetic interpretation of static switching of electric-field-induced magnetization in Cr 2 O 3 was similar to that of the ordinary ferromagnetic materials.

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