Multiferroic magnetoelectric composite nanostructures

Multiferroics are attracting increasing interest and provoking much research activity driven by the profound physics of these materials, the coexistence and coupling of ferroelectric and magnetic orders, and the potential applications in novel multifunctional devices such as sensors, transducers, memories and spintronics. Multiferroic magnetoelectric (ME) composite systems, such as ferromagnetic-ferroelectric heterostructures, which offer a novel route for integrating ferroelectric and ferromagnetism, have been widely studied in recent years. In these ME composite systems, ME coupling is strain-mediated, that is, the strain induced in one component, either by magnetostriction in the ferromagnetic or by the piezoelectric effect in the ferroelectric, is transferred to the other component, altering the polarization or magnetization. This article reviews the magnetic-field control of electric polarization and its converse effect, electric-field control of magnetization, in multiferroic ME composite nanostructures. The review focuses on three kinds of ME nanostructures: vertical heterostructures, horizontal heterostructures and particulate nanocomposite films. Theoretical approaches, such as Green's function methods, the phase field model and first-principles methods, have been used to simulate and predict the ME coupling effect in such nanostructures. Herein we briefly describe the potential applications of the ME nanostructured composites using representative examples, and outline the challenges and promising future for this field.