A7: Electronic, geometric, and magnetic properties of multiferroic heterostructures
Main topic of this project is the microscopic understanding of the magneto-electric coupling across the interface of two-component multiferroics. Therefore, it is important to study the electronic, geometric and also the magnetic properties of these systems. Building upon the previous studies of thin Fe and Co layers on BaTiO3(001) (BTO), now XMCD and MOKE experiments are extended to thin CoFe2O4 layers (as starting point for other oxidic spinells and perovskites) and also to systems with BTO prepared as thin layer (e.g., on Pt or Pd). One goal is to detect changes of the magnetic properties for different states of polarization of BTO (“switching”), in particular in an element specific way. In order to obtain a close connection to theory, studies of the geometric structure by LEED and photoelectron diffraction (XPD) and by high-resolution near edge fine structure (XANES) are added. The latter two techniques are specifically suitable for systems without long-range order or with specific structuring (steps, islands). Adding PLD as preparation method extends the possibilities for the growth and enables the study of more complex systems (e.g., La1-xSrxMnO3).
High-resolution XANES measurements of the studied systems (e.g., CoFe2O4/BTO(001), Fe/BTO(001) and respective layer systems on Pt or Pd) will be compared to theoretical calculations in the framework of a fully-relativistic ab initio theory of x-ray absorption. Structure data will be obtained from LEED and XPD experiments with the help of simulations and/or ab initio methods. One task in the theory section will be to extend the description of the results of electron spectroscopy methods, which are currently based on density functional theory (DFT) of the ground state in local density approximation (LDA), to a description in terms of excited states, taking into account inelastic losses (self energy) and the electron-hole interaction. Aim is to obtain a quantitative interpretation of experimental results, which would enable a more detailed understanding of the geometric and electronic structure and of their changes due to the magneto-electric coupling for the systems studied.
Principal Investigators
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Prof. Dr. Reinhard Denecke ⇒
phone: +49 (0) 341/97 36451 fax: +49 (0) 341/97 36399 |
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PD Dr. Angelika Chassé ⇒
angelika.chasse@physik.uni-halle.de phone: +49 (0) 345/55 25436 fax: +49 (0) 345/55 25446 |
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PD Dr. Karl-Michael Schindler ⇒
karl-michael.schindler@physik.uni-halle.de phone: +49 (0) 345/55 25363 fax: +49 (0) 345/55 27160 |
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