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In the on-going process of electronic device miniaturization new concepts are developed by utilizing hybrid systems. For this purpose the tailoring of the magnetic properties in these nanoscale systems is essential. We make use of hybrid systems that consist of a combination of magnetic molecules, graphene, thin films as well as magnetic nanopillars. Surface and interface effects are crucial to achieve new functionalities in these structures. This shall be demonstrated by means of two examples: 1) The magnetic coupling of paramagnetic molecules to ferromagnetic surfaces can be tailored by the help of an intermediate layer of atomic oxygen or graphene [1-4]. The fundamental understanding of the relevant interactions for the coupling is possible by combination of experimental and theoretical results utilizing ab initio calculations. 2) Ferrimagnetic CoFe2O4 (CFO) nanopillars embedded in a ferroelectric BaTiO3 (BTO) matrix are an example for a two-phase magnetoelectrically coupled system [5]. In particular, the [1] H. Wende et al., Substrate-induced magnetic ordering and switching of iron porphyrin molecules, Nature Materials 6, 516 (2007). [2] H. Wende, Molecular magnets: How a nightmare turns into a vision, Nature Materials 8, 165 (2009). [3] M. Bernien et al., Tailoring the Nature of Magnetic Coupling of Fe-Porphyrin Molecules to Ferromagnetic Substrates, Phys. Rev. Lett. 102, 047202 (2009). [4] S. Bhandary et al., Graphene as a Reversible Spin Manipulator of Molecular Magnets, Phys. Rev. Lett. 107, 257202 (2011). [5] C. Schmitz-Antoniak et al., Electric in-plane polarization in multiferroic CoFe2O4/BaTiO3 nanocomposite tuned by magnetic fields, Nature Communications 4:2051 doi: 10.1038/ncomms3051 (2013).

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Heiko Wende, University of Essen-Duisburg
Seminar Room of the Institute of Physics II
Contact: Thomas Michely