Session W13: Focus Session: Iron Pnictides and Other Novel Superconductors XIV: ARPES

11:15 AM–2:03 PM, Thursday, March 19, 2009
Room: 309

Chair: Norman Mannella, University of Tennessee, Knoxville

Abstract ID: BAPS.2009.MAR.W13.11

Abstract: W13.00011 : Observation of an orbital selective electron-mode coupling in Fe-based high-Tc superconductors

1:15 PM–1:27 PM

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Authors:

Pierre Richard
(WPI, Tohoku University)

T. Sato
K. Nakayama
(Dep. Physics, Tohoku University)

S. Souma
(WPI, Tohoku University)

Y.-M. Xu
(Boston College)

G.F. Chen
J.L. Luo
N.L. Wang
H. Ding
The recent discovery of Fe-based superconductors with critical temperatures up to 56 K raises the prospect of unconventional superconducting pairing mechanism. While the electronic pairing in conventional superconductors is mediated by phonons, its nature in the Fe-based high-$T_{c}$ superconductors is unknown. A direct signature of an electron-mode coupling is an anomaly in the electronic energy dispersion (kink). For example, previous angle-resolved photoelectron spectroscopy (ARPES) studies revealed a kink in cuprates, which is believed to be linked to the pairing. We report an ARPES observation of a kink around 25 meV in the dispersion of superconducting Ba$_{0.6}$K$_{0.4}$Fe$_{2}$As$_{2}$ that nearly vanishes above $T_{c}$. The energy scale of the related mode (13$\pm$2 meV) and its strong dependence on orbital and temperature indicates that it is unlikely related to phonons. Moreover, the momentum locations of the kink can be connected by the antiferromagnetic wavevector. Our results point towards an electronic origin of the mode and the superconducting pairing in the Fe-based superconductors, and strongly support the anti-phase s-wave pairing symmetry.