Planar tunnel junction on oxygen doped iron telluride thin films

Since its discovery, iron based superconductivity has garnered much interest from the research community for its potential in both application and fundamental science. One of the questions awaiting an answer is the pairing symmetry of this new class of superconductors. Recently, Koshelev and Stanev proposed a fingerprint of s$+$- symmetry in the NIS tunneling spectrum where the iron based superconductor is proximity-coupled to a thin s-wave superconductor[1]. We have prepared oxygen doped iron telluride (FeTe:Ox) thin films, along with an in-situ grown tunnel barrier and top electrode by Molecular Beam Epitaxy (MBE). We have fabricated them into planar tunnel junction and will report the temperature dependence of both tunneling and point contact spectra. [1]. A. E. Koshelev and V. Stanev, EPL (Europhysics Letters) \textbf{96} (2), 27014 (2011).