The structure of the superconducting order parameter in the iron-pnictide superconductor BaFe2(As0.67P0.33)2 (Tc=31 K) with line nodes is studied by the angle-resolved thermal conductivity measurements in a magnetic field rotated within the basal plane. We find that the thermal conductivity displays distinct fourfold oscillations with minima when the field is directed at ±45 with respect to the tetragonal a axis. We discuss possible gap structures that can account for the data, and conclude that the observed results are most consistent with the closed nodal loops located at the flat parts of the electron Fermi surface with high Fermi velocity.
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|Publication status||Published - 2011 Aug 18|
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics