Berlin 2012 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 33: Superconductivity, Measuring Devices, Matter at Low Temperature: Poster Session

TT 33.7: Poster

Wednesday, March 28, 2012, 15:00–19:00, Poster B

Three-dimiensional Fermi surface of Iron-pnictide superconductor Ba_1−xK_xFe₂As₂ — •Masaki Kobayashi^1,2, Vladimir N. Strocov¹, Elia Razzoli^1,3, Ming Shi¹, Thorsten Schmitt¹, Xiaoping Wang^1,4, Yaobo Huang⁴, Hong Ding⁴, Masaharu Oshima², and Luc Patthey¹ — ¹Swiss Light Source, Paul Scherrer Institut, Villigen, Switzerland — ²Department of Applied Chemistry, University of Tokyo, Tokyo, Japan — ³Laboratory for Synchrotron and Neutron Spectroscopy, EPFL, Lausanne, Switzerland — ⁴Institute of Physics, Chinese Academy of Science, Beijing, China

Iron-based superconductors have attracted much attention because of the unexpected high transition temperatures of the superconducting state. Investigation of bulk three-dimensional electronic structure will provide further understanding of the superconducting properties of Ba_1−xK_xFe₂As₂ (BKFA). Here, we report investigations of the shape and k_z-dependence of the Fermi surface (FS) in BKFA with soft X-ray ARPES, taking into advantage enhanced bulk sensitivity and intrinsic k_z resolution achieved in the soft-X-ray range.

The experimental FS measured at energies around 900 eV show modulations along the k_z direction corresponding to the Brillouin zone periodicity in BKFA. The in-plane FS shapes alternate between a circle-like and flower-like appearances when going from the Γ point to the higher Brillouin zones. Furthermore, we observed clear polarization dependences of the FS, allowing separation of different valence bands. The results provide with experimental information on the dimensionality and orbital character of FSs of BKFA.