Dresden 2009 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 40: Superconductivity: Ferropnictides 1

TT 40.16: Vortrag

Donnerstag, 26. März 2009, 18:15–18:30, HSZ 03

Pressure-induced structural and magnetic transitions in the 122 iron arsenide compounds — •Yuzhong Zhang, Hem Kandpal, Ingo Opahle, Harald Jeschke, Claudius Gros, and Roser Valenti — Institut für Theoretische Physik, Goethe Universität Frankfurt, Germany

The parent compounds of the new superconductor family (Ca, Sr, Ba)Fe₂As₂ under hydrostatic pressure at low temperature are investigated within the framework of ab initio molecular dynamics. Structural phase transitions from orthorhombic to tetragonal phase are detected in all these materials. These transitions are simultaneously accompanied by magnetic phase transitions from a stripe-type antiferromagnetic state to a paramagnetic state. While the obtained first-order phase transition in CaFe₂As₂ is consistent with the experimental results, we predict from our calculations that the phase transitions in SrFe₂As₂ and BaFe₂As₂ are of weak first order and continuous order, respectively. Analysis of Fermi surfaces, partial density of state as well as bandstructures as a function of chemical and hydrostatic pressure reveals the differences among these compounds. Finally we discuss, out of our calculations, the possible mechanism of the superconducting states.