Concept of artificial magnetoelectric materials via geometrically controlling curvilinear helimagnets

A novel type of artificial magnetoelectric material, which allows an electric field-induced deterministic switching between magnetic states without influencing intrinsic magnetic parameters, is proposed. It refers to three dimensional curvilinear helimagnets, e.g. torsion springs, embedded in a piezoelectric matrix. In contrast to conventional strain-coupled magnetoelectric heterostructures based on piezoelectric-magnetostrictive bilayers, we exploit the geometrical coupling of the matrix to the curvilinear helimagnet with intrinsic chiral Dzyaloshinskii–Moriya interactions. Namely, the magnetic state is modified due to the change of geometrical parameters of the curved nanomagnet. Theoretically, the essence of the proposal is analysed for a deformable torsional spring made of helimagnetic material. In response to the geometrical change magnetic phase transition between the homogeneous and a periodically modulated state can be driven in a wide range of geometrical parameters. Resulting transformations of the average magnetization from non-zero to zero value can be uniquely assigned to logical '1' and '0'. As the chiral magnetic properties are easier to control by mechanical distortion than effective anisotropies, our concept should lead to a robust design of novel magnetoelectric devices. (paper)