A-site magnetic spinels exhibit a variety of magnetic ground states, such as long-range antiferromagnetic order, spin glass or spin liquid state, depending on the strengths of the nearest-neighbour and next-nearest-neighbour exchange interactions. According to the Landau theory, cubic A-site magnetic spinels with a collinear antiferromagnetic order should exhibit the linear magnetoelectric effect below the Néel temperature. The cubic spinel oxide, Co3O4, with an easy-axis type antiferromagnetic state below TN = 30 K, provides an ideal platform to study the predicted magnetoelectric effect.
In this talk, I will discuss about our recent results on the linear magnetoelectric effect in a single crystal of Co3O4. A magnetoelectric mono-domain state can be created either by poling simultaneously with magnetic and electric fields or by applying them in-situ, where the sign of the magnetoelectric coefficient depends on the relative signs of the magnetic and electric fields. I will demonstrate that the magnetoelectric domains can be switched in situ by both moderate magnetic and electric fields. Since the magnetoelectric effect is solely determined by the orientation of the antiferromagnetic Néel vector in this compound, these findings imply the in-situ control of antiferromagnetic domains in Co3O4, which needs to be verified by polarized neutron diffraction experiments.
Dr. Christian Franz