Ab initio study of 3d systems under high pressure

Abstract: Since many years humanity is trying to understand processes deep inside our planet. That's why in particular high-pressure research is developing very fast these days. Thanks to the invention of the diamond anvil cells (DAC) it is now possible to measure x-ray spectra and investigate properties of matter under very high compression. In recent experiments the applied pressure exceeds the Mbar range, so we can put a sample into the conditions, corresponding to Earth's core. Of course, such pressure affects electronic structure dramatically and very often different phase transitions take place. It is of particular interest to study transition metals because it is a direct way to understand the relation between crystal structure and stability of magnetism. We try to address this problem by means of first-principle calculations based on Density Functional Theory (DFT). Our major goal is to understand pressure-driven changes in electronic and magnetic structure on microscopic level. In this talk I will show our results on iron-containing alloys: FePd3 and Fe3Al. Both of these systems exhibit different magnetic transtions under applied pressure, which were observed experimentally. Our results indicate strong changes in exchange interactions and significant variation of the Curie temperature in these compounds under compression.