Frustration and relaxation of antiferromagnetic domains reversed by magneto-electric field cooling in a Pt/Co/Au/Cr2O3/Pt-stacked film

Using magnetic domain observations, we investigated the reversal process of the perpendicular exchange bias polarity resulting from the antiferromagnetic Cr2O3 domain reversal driven by magneto-electric field cooling (MEFC). The exchange bias polarity changed from negative to positive with increasing electric field during MEFC. The relevant change in the magnetic domain revealed the stochastic appearance of the reversed magnetic domains that exhibit the positive exchange bias. The local magnetization curves suggest that the antiferromagnetic domain state after MEFC was frustrated because of energy competition between the interfacial exchange coupling and the bulk magneto-electric effect. The frustrated nature of the magnetic domain structure is supported by the training effect of the exchange bias after MEFC.