Berlin 2018 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 35: Superconductivity: Fe-based Superconductors - 122 and Theory
TT 35.5: Talk
Tuesday, March 13, 2018, 10:30–10:45, A 053
Mass enhancements and band shifts in hole overdoped Fe-based pnictide superconductors: KFe2As2 and CsFe2As2 — •S.-L. Drechsler1, H. Rosner2, V. Grinenko3, S. Aswartham1, I. Morozov4, L. Ming4, A. Boltalin4, K. Kihou5, C. H. Lee5, T. K. Kim6, D. Evtushinsky7, J.M. Tomczak8, S. Johnston9, and S. Borisenko1 — 1IFW-Dresden, Germany — 2MPI-CPfS Dresden, Germany — 3TU Dresden, Germany — 4Moscow University, Russia — 5AIST, Tsuk. Japan — 6Diamond Light Source, U.K. — 7Ec. de Fed., Lausanne, Switzerland — 8Vienna-University of Technology, Austria — 9Tennesee University, Knoxville, USA
The interplay of high- and low energy (LE) mass renormalizations with band shifts as seen in the positions of van Hove singularities (VHS) in the normal state of the strongly correlated and most hole-overdoped AFe2As2 (A122), A = K,Rb,Cs Fe pnictides is discussed phenomenologically from ARPES data and band structure (GGA) with full spin-orbit coupling and microscopically applying the GW-self-energy. The increase of the Sommerfeld coefficient γ from K122 to Cs122 is ascribed to an enhanced coupling to LE bosons in the vicinity of a quantum critical point to an yet unknown incommensurate phase different from the tetragonal Mott phase. We find no sizable increase of correlation for Cs122 in contrast to scenarios proposed in the literature. The ARPES positions of VHS as compared with GGA and GW results point to slightly weaker correlations in accord with the low-T susceptibility data and the reduced Wilson ratio χ(0)/γ. Other quasi-2D systems with generic VHS and their el-el interactions are briefly discussed.