B5: Magnetic and electric properties of ultrathin oxide films
In this project embedded oxide layers with a thickness of only a few unit cells will be fabricated and their electric and magnetic properties will be investigated. This work is motivated by our previous studies within the SFB. We could especially show that ferromagnetic order and metallic conductivity are stable in ultrathin La0.7Sr0.3MnO3 layers, when these are in contact with SrRuO3 layers. Even if the physical mechanism of this proximity effect has not yet been clarified, it was impressively shown that embedded layers may have completely different properties than layers with free surfaces. These studies will be continued in three directions. (1) To date only superlattices were studied, such that the total sample thickness was rather large, even in case of ultrathin single layers. This prevented the study of electrostatic doping effects. In the new SFB period embedded ultrathin single layers will be fabricated and investigated. Via a gate electrode the influence of charge density modulations on the magnetotransport properties will be studied. The relevant materials for this are manganites as well as SrRuO3, LaNiO3 und SrVO3. (2) The ferromagnetic Curie temperatures of perovskites are too low for potential applications. Ferrites, however, have high Curie temperatures and magnetic properties that might be tailored by defects. Therefore equivalent structures based on ferrites and conducting spinels will be fabricated and investigated. As a starting point Fe3O4 and CoFe2O4 will be used as ferrimagnetic components and MgIn2O4 and ZnGa2O4 as conducting spinels. (3) In the third branch exotic substrates with multiferroic or ferrimagnetic order, e.g. YMnO3 or Fe3O4 crystals, will be used. The coupling between magnetic and electric properties of the substrates and films grown on top will be studied by magnetotransport measurements. Apart from the vertical constriction due to the film thickness exchange-bias and magnetic proximity effects will be further studied in lateral nanostructures.
Principal Investigators
|
Prof. Dr. Michael Ziese ⇒
phone: +49 (0) 341/97 32752 fax: +49 (0) 341/97 32668 |
|
|
Prof. Dr. Pablo D. Esquinazi ⇒
phone: +49 (0) 341/97 32751 fax: +49 (0) 341/97 32668 |
|