P7

Investigation of the electronic and magnetic structure of materials with high spin polarization by means of experimental and theoretical methods (Felser / Schönhense)

This project examines the electronic and magnetic structure of half-metallic ferromagnets by using experimental and theoretical methods and employing quantitative spin analysis. The main emphasis of the project is focused on Heusler compounds and double perovskites. In this project, the occupied states of these materials are spectroscopically examined and complement the spectroscopic experiments of P 10 (Cinchetti / Aeschlimann). The basic materials produced in P 1 (Felser), P 2 (Jakob), and P 4 (Tremel), as well as functionalized materials from P 11 (Jourdan) and P 12 (Ando) are investigated. The calculations focus on ground state properties and are complemented by calculations of P 6 (Blümer / van Dongen). The combination of experiment and theory in one project allows easy coordination and close cooperation for comparisons between experimental results and calculated hypotheses.

• The theoretical part of the project uses ab initio calculations to predict new compounds, and to explain the properties of the compounds produced and investigated in the other projects of the research unit. In the coming period, the focus will also be on the calculation of Curie temperatures as well as phonon and magnon excitations in Heusler compounds.
• The main experimental task is the spectroscopic investigation of the bulk electronic structure by means of synchrotron radiation based hard X-ray photoemission (HAXPES), as well as spin- and angular-resolved photoemission (SPARPES) in combination with spin-resolved photoemission microscopy (PEEM). SPARPES allows for spin-resolved band-mapping, but has the disadvantage of high surface sensitivity. This problem can be overcome by using HAXPES with its true bulk sensitivity.