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TT: Fachverband Tiefe Temperaturen

TT 36: Superconductivity: Fe-based Superconductors - Fe(Se,Te), LiFeAs, and other Materials

TT 36.2: Vortrag

Mittwoch, 13. März 2013, 09:45–10:00, H18

Phonon driven phase transition in FeSe — •Michael Fechner and Nicola Spaldin — ETH Zurich, Department for Material Theory,CH-8093 Zurich, Switzerland

One of the chemically simplest, but physically complex, iron based superconductors is FeSe. Here we present results from first-principle calculations of its competing magnetic phases. In particular we compare calculated electronic properties of coherent FeSe films under different tensile strains, corresponding to SrTiO₃ and MgO substrates, and electron/hole doping with experimental findings. The main result is that for moderate applied strain the spin density wave (SDW) in FeSe is suppressed, whereas there is a sudden strong enhancement for larger strain. Given that superconductivity disappears in highly strained FeSe on MgO, our results thus give an interesting insight in which energy ranges the SDW still compete with superconductivity. The results are finally discussed with respect to the possibility of phonon driven superconductivity in FeSe.