B8: Strain, stress and lattice dynamics of multiferroic systems
This project is devoted to the experimental investigation of mechanical strain and lattice dynamics at interfaces of oxidic and multiferroic thin film systems as well as their theoretical description within ab-initio calculations.
For the functionality of multiferroic layered systems the coupling of magnetic and ferroelectric properties via strain at the interface is believed to be a fundamental mechanism. For the coupling of piezoelectric-induced strain and magnetic anisotropy the magnetostrictive properties of the ferromagnetic component are most important. Based on our earlier work on metallic systems we expect that the magnetostrictive properties are crucially depending on small changes of the lattice parameters. For the proper description of multiferroic coupling across interfaces the understanding of lattice strain and relaxation for thin films and their relation to the ferroelectric and magnetic properties is prerequisite. At this point the experimental determination of surface stress can give important quantitative results. However only in combination with lattice dynamics and ab-initio calculations a deeper insight into the balanced interplay between strain, stress, phonon softening and structure is possible. This project aims at a description of these phenomena beyond the often used simple models with interatomic force constants.
Principal Investigators
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Prof. Dr. Wolf Widdra ⇒
wolf.widdra@physik.uni-halle.de phone: +49 (0) 345/55 25360 fax: +49 (0) 345/55 27160 |
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PD Dr. Dirk Sander ⇒
phone: +49 (0) 345/55 82660 fax: +49 (0) 345/55 11223 |
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Dr. Valeri Stepanyuk ⇒
phone: +49 (0) 345/55 82645 fax: +49 (0) 345/55 11223 |
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