Equilibrium magnetization at the boundary of a magnetoelectric antiferromagnet

Symmetry arguments are used to show that a boundary of a magnetoelectric antiferromagnet has an equilibrium magnetization. This magnetization is coupled to the bulk antiferromagnetic order parameter and can be switched along with it by a combination of E and B fields. As a result, the antiferromagnetic domain state of a magnetoelectric can be used as a non-volatile switchable state variable in nanoelectronic device applications. Mechanisms affecting the boundary magnetization and its temperature dependence are classified. The boundary magnetization can be especially large if the boundary breaks the equivalence of the antiferromagnetic sublattices.