paper

Three-dimensional Resonance in superconducting BaFeNiAs

arXiv:0812.1354 · doi:10.1103/PhysRevLett.102.107006

Abstract

We use inelastic neutron scattering to study magnetic excitations of the FeAs-based superconductor BaFeNiAs above and below its superconducting transition temperature K. In addition to gradually open a spin gap at the in-plane antiferromagnetic ordering wavevector , the effect of superconductivity is to form a three dimensional resonance with clear dispersion along the c-axis direction. The intensity of the resonance develops like a superconducting order parameter, and the mode occurs at distinctively different energies at and . If the resonance energy is directly associated with the superconducting gap energy , then is dependent on the wavevector transfers along the c-axis. These results suggest that one must be careful in interpreting the superconducting gap energies obtained by surface sensitive probes such as scanning tunneling microscopy and angle resolved photoemission.

arXiv comment5 pages, 4 figures

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