Regensburg 2016 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 46: Superconductivity: Fe-based Superconductors - FeSe

TT 46.7: Vortrag

Mittwoch, 9. März 2016, 12:00–12:15, H19

Superconductivity and spin excitations in orbitally ordered FeSe — •Andreas Kreisel1, Shantanu Mukherjee1,3, Peter J. Hirschfeld2, and Brian M. Andersen11Niels Bohr Institute, University of Copenhagen, Denmark — 2University of Florida, Gainesville, FL, USA — 3Dept. of Physics, State University of New York at Binghamton, Binghamton, NY, USA

We provide a band-structure with low-energy properties consistent with recent photoemission and quantum oscillations measurements on the Fe-based superconductor FeSe[1], including a mean-field like orbital ordering in the dxz/dyz channel, and show that this model also accounts for the temperature dependence of the measured Knight shift and the spin-relaxation rate[2]. An RPA calculation of the dynamical spin susceptibility yields spin excitations which are peaked at wave vector (π,0) in the 1-Fe Brillouin zone, with a broad maximum at energies of order a few meV. Furthermore, the superconducting gap structure obtained from spin fluctuation theory exhibits nodes on the electron pockets, consistent with the ’V’-shaped density of states measured by tunneling spectroscopy on this material. The redistribution of spectral weight in the superconducting state creates a (π,0) "neutron resonance" as seen in recent experiments[3]. Comparing to various experimental results, we give predictions for further studies.

[1] S. Mukherjee et al., PRL 115, 026402 (2015)

A. Kreisel, et al., arXiv:1506.03593

[2] S.-H. Baek et al., Nat. Mater. 14, 210 (2015)

A. E. Böhmer et al., PRL 114, 027001 (2015)

[3] M.C. Rahn et al., PRB 91, 180501 (2015)

Q. Wang, et al., arXiv:1502.07544

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