### 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.W13.7

### Abstract: W13.00007 : Momentum dependence of the superconducting gap in NdFeAsO$_{1-x}$F$_x$ single crystals measured by angle resolved photoemission spectroscopy

12:27 PM–12:39 PM

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#### Authors:

Takeshi Kondo
(Ames Lab. and Dept. of Physics and Astronomy, Iowa State University)

A.F. Santander-Syro
(Ames Lab. and Dept. of Physics and Astronomy, Iowa State University)

O. Copie
(Ames Lab. and Dept. of Physics and Astronomy, Iowa State University)

Chang Liu
(Ames Lab. and Dept. of Physics and Astronomy, Iowa State University)

M.E. Tillman
(Ames Lab. and Dept. of Physics and Astronomy, Iowa State University)

J. Schmalian
(Ames Lab. and Dept. of Physics and Astronomy, Iowa State University)

S.L. Bud'ko
(Ames Lab. and Dept. of Physics and Astronomy, Iowa State University)

P.C. Canfield
(Ames Lab. and Dept. of Physics and Astronomy, Iowa State University)

A.D. Kaminski
(Ames Lab. and Dept. of Physics and Astronomy, Iowa State University)

We use angle resolved photoemission spectroscopy (ARPES) to study the momentum dependence of the superconducting gap in NdFeAsO$_{1-x}$F$_x$ single crystals. We find that the $\Gamma$ hole pocket is fully gapped below the superconducting transition temperature. The value of the superconducting gap is 15 $\pm$ 3 meV and its anisotropy around the hole pocket is smaller than 20$\%$ of this value. This is consistent with an isotropic or anisotropic s-wave symmetry of the order parameter or exotic d-wave symmetry with nodes located off the Fermi surface sheets. This is a significant departure from the situation in the cuprates, pointing to possibility that the superconductivity in the iron arsenic based system arises from a different mechanism.

To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2009.MAR.W13.7