Regensburg 2013 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 69: Superconductivity: Fe-based Superconductors - Theory
TT 69.3: Vortrag
Freitag, 15. März 2013, 10:00–10:15, H21
Lattice dynamics of binary FeAs from first principles — •Alexander Herbig1,2, Rolf Heid2, and Klaus-Peter Bohnen2 — 1Physikalisches Institut, Karlsruher Institut für Technologie — 2Institut für Festkörperphysik, Karlsruher Institut für Technologie
Since the discovery of superconductivity in fluorine-doped LaFeAsO in 2008, the research on the so-called iron pnictides is rapidely developing. One of their building blocks, the FeAs layers, seem to play an important role for the physical properties of the iron pnictides. The rare theoretical work on binary FeAs motivated us to perform ab-initio calculations of electronic structure and lattice dynamics of this compound by means of density functional and linear response theory within the mixed-basis pseudopotential method.
We compared different collinear magnetic states with same crystal structure. Thereby an antiferromagnetic state, which is the best collinear approximation to the experimentally observed spin density wave [1], exhibits the lowest total energy in good agreement with previous calculations [2]. Without spin polarization, we found unstable phonon modes while magnetism stabilizes the phonon spectra.
Until now, no direct measurements of the phonon spectra are available. For the purpose of validating our phonon calculations we calculated the phononic heat-capacity and
found good agreement with experiment.
[1] E. E. Rodriguez et al., Phys. Rev. B 83, 134520 (2011)
D. Parker, I. I. Mazin, Phys. Rev. B 83, 180403 (2011)