Multiple Energy Gaps via Soft Point Contact Spectroscopy of Doped Ba_(1-x)K_xFe₂As₂

We report progress in our measurements of multiple energy gaps in Ba_(1-x)K_xFe₂As₂ with different K, Co and P dopings. These iron-based superconductors provide a new platform where multi-band superconductivity can be studied. The observed multiple energy gaps depending on the crystal growth conditions and on which tunneling directions are made accessible during the sample preparation process. We discuss how we have made electrical contact to crystal samples obtained by applying a small amount of silver paint using a sharp-tipped wire and measuring the resulting conductance. We have been moderately successful using this technique and have observed observe peaks and broad shoulders in the conductance - which can correspond to multiple energy gaps; some peaks correlate well with data from oher groups, while other new peaks are unexplained. Finally, we report progress on exploring a micropipette-based delivery of silver paint for more controlled method of contacting crystals. All measurements in this work were performed by undergraduates.