Tunneling spectroscopy and transport properties of FeSe thin films

• Applicant: Professor Dr. Martin Jourdan
• Subject Area: Experimental Condensed Matter Physics
• Term: from 2011 to 2015
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 189908852

The aim of this project is to gain an improved understanding of the mechanism of superconductivity of ironpnictides/ -chalocogenides and related compounds. We investigate the compound FeSe (and doped FeSe1-xTex), the structurally simplest representative of this class of materials. Epitaxial thin films are used as samples with a defined geometry and well-ordered surface, as necessary or advantageous for the intended investigations.A study of the films thickness and substrate dependence of the superconducting transition temperature focusing on lattice distortions generated by the substrate – thin film interaction (epitaxial stress) will help to improve the understanding of the pronounced preparation condition dependence of the sample properties.We aim at the direct investigation of the superconducting energy gap and the mechanism of superconductivity (strong coupling features) by tunneling spectroscopy on planar junctions. Additionally, by film deposition on substrates with grain boundaries in-plane Josephson junctions for the investigation of the order parameter symmetry can be realised. Supplementary, angular dependent measurements of the upper critical field can provide access to the symmetry of the superconducting order parameter. Hall-effect and Thermopower measurements on FeSe1-xTex thin films give information concerning the doping level dependent Fermi-surfaces.

• DFG Programme: Research Grants