Martin Luther University Halle-Wittenberg

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A4: Electronic ground-state and excited-state properties of complex oxide structures

Main goal of the project is the ab initio investigation of the magnetic proximity effect in complex oxidic heterostructures. Furthermore, electronic properties of thin oxidic films on metal substrates will be investigated. The oxidic heterostructures are formed from non-magnetic oxides and magnetic materials (magnetic oxides, transition metals). The modifications of the electronic and magnetic structure of the non-magnetic oxide due to the neighborhood of the magnetic component will be studied. The properties of such systems are strongly influenced by the crystalline structure and the exchange interactions at the interface. The ab inito investigations will be concentrated on those two aspects. The methods, necessary for such investigations, have been developed in this project in the past. The treatment of oxidic materials by ab initio methods requires a correct description of the correlation effects. In our approach (KKR Greenís function code HUTSEPOT) two methods are implemented: self-interaction correction (SIC) and LDA+U method. Structural information at interfaces and surfaces are determined by the efficient pseudopotential code VASP. The strong collaboration with other projects of the SFB to gain structural information will be continued. For the investigation of magnetic properties the magnetic force theorem and linear response theory are used.

In the focus of the investigations are especially the following systems: Co/Pb(Zr,Ti)O3/LaxSr1-xMnO3, Co/Pb(Zr,Ti)O3/SrRuO3, SrRuO3/LaxSr1-xMnO3 and SrTiO3/LaxSr1-xMnO3. Those systems are investigated in several experimental projects of the SFB. The influence of the interface geometry, the number of free electrons and of the defects at the interface on the proximity effect will be studied in detail. The investigation of oxidic films on metal substrates will be extended to quasi-crystalline oxidic films.

The influence of lattice defects, dopants and adatoms on the surface will be further investigated. Such defects are important for the basic mechanisms of defect-induced magnetism. Defect-induced magnetism will be investigated in B1 experimentally and theoretically.

Principal Investigators

Prof. Dr. Arthur Ernst ⇒

phone: +49 (0) 345/55 82666
fax: +49 (0) 345/55 11223

PD Dr. Arthur Ernst

PD Dr. Arthur Ernst

Prof. Dr. Wolfram Hergert ⇒

phone: +49 (0) 345/5  525445

fax: +49 (0) 345/55 25446

Prof. Dr. Wolfram Hergert

Prof. Dr. Wolfram Hergert