Regensburg 2013 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 69: Superconductivity: Fe-based Superconductors - Theory
TT 69.2: Vortrag
Freitag, 15. März 2013, 09:45–10:00, H21
Finite temperature and pressure molecular dynamics for BaFe2As2 — •Steffen Backes and Harald Jeschke — Institut für Theoretische Physik, Goethe-Universität Frankfurt, Germany
We investigate the temperature and pressure dependence of the structural and electronic properties of the iron pnictide superconductor BaFe2As2. We use density functional theory based Born-Oppenheimer molecular dynamics simulations to study the system at temperatures from T=5 K to 150 K and pressures from P=0 to 30 GPa. When increasing the pressure at low temperature, we find the two transitions from orthorhombic to tetragonal to collapsed tetragonal that are also observed in zero temperature structure relaxations and in experiment. However, the first of these transitions is considerably smeared out at finite temperature. We find a negative slope of the tetragonal to collapsed tetragonal transition in the T-P phase diagram in very good agreement with experiment. We also analyze the electronic structure of BaFe2As2 at finite temperature and work out differences between the time averaged band structure and Fermi surface at finite temperature compared to the known zero temperature results. Our results should be helpful for understanding some contradictions in experimental reports for BaFe2As2 under high pressure.