Artificially controlled magnetic domain structures in ferromagnetic dots∕ferroelectric heterostructures

A variation in the magnetization and magnetic domain structures of epitaxial Fe dots on a single crystal BaTiO3 substrate is demonstrated in association with the structural phase transition of ferroelectric BaTiO3. The temperature dependent magnetization of Fe dots drops suddenly at 282K and increases again at 189K with decreasing temperature. The variations clearly correspond to the successive structural phase transitions of BaTiO3 from tetragonal to orthorhombic phases and from orthorhombic to rhombohedral phases. After a thermal cycle between room temperature and 150K passing through these phase transitions, the initial magnetic domain structure of Fe dots with an enclosed magnetic flux structure changes to a single-domain-like structure due to interfacial strain between Fe and BaTiO3 arising from possible switching of c-axis orientation of BaTiO3 substrate.