Investigation of Superconducting Gap Structure in   TbFeAsO$_{0.9}$F$_{0.1}$ using Point Contact Andreev Reflection
  Bulk samples of TbFeAsO$_{0.9}$F$_{0.1}$ (T$_{c}$(on) = 50K) were measured by point contact Andreev reflection spectroscopy. The spectra show unambiguous evidence for multiple gap-like features plus the presence of high bias shoulders. By measuring the spectra as a function of temperature with both gold and superconducting niobium tips, we establish that the gap-like features are associated with superconducting order parameter in this material. We discuss whether the well defined zero bias conductance peak that we observe infrequently is associated with a nodal superconducting order parameter. 
K.A. Yates, K. Morrison, Jennifer A Rodgers, George BS Penny,   Jan-Willem G Bos, J. Paul Attfield, L.F. Cohen