Sukhov A., Chotorlishvili L., Jia C.-L., and Berakdar J.

In this chapter we present a theoretical approach for modeling the coupled polarization-magnetization dynamics in composite multiferroic nanostructures. The free energy functional is based on coupling established expressions for the the Ginzburg-Landau-Devonshire polarization free energy density with the Landau-Ginzburg magnetization free energy density. The polarization/magnetization coupling term depends on the nature of the underlying magnetoelectric interaction. As an example we inspect the role of an emerging non-collinear spin order at the ferroelectric/magnetic interface and discuss how this mechanism is reflected in the total free energy density. We present and analyze numerical results for the coupled polarization and magnetization dynamics driven by external electric and magnetic fields and show how this dynamics can be accessed experimentally via ferromagnetic resonance in nanostructured multiferroic BaTiO₃/Fe or BaTiO₃/Co composites. As a way for robust signal transmission and conversion, solitonic excitations are envisaged. The finding is that initially prepared magnetic (electric) solitonic signals propagate towards the interface where they are efficiently converted into electric (magnetic) signals. In a further section we explore the potential of multiferroics for quantum information applications.

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