C-axis transport of pnictide superconductors

• Applicant: Professor Dr. Paul Müller (†)
• Subject Area: Experimental Condensed Matter Physics
• Term: from 2010 to 2017
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 168285900

Anisotropy is a critical issue for all high-Tc superconductors. Both fundamental questions of the mechanism and applications depend sensitively on anisotropic transport parameters. We plan to investigate the transport anisotropy of pnictide single crystals by dc measurements and the anisotropy of magnetization using 2DEG Hall-probes. As the coherence length anisotropy is near the limit of Josephson coupling between the FeAs planes, rather high c-axis critical current densities can be expected. This defines a new regime of intrinsic Josephson effects. Intrinsic dc and ac Josephson effects as well as macroscopic quantum tunnelling will be studied. We have discovered a rather spectacular effect. By current injection in c-axis direction, we can change the doping level rather effectively. We will characterize the modifications of the superconducting and insulating layers. One attractive goal would be increasing the critical temperatures by doping without significant lattice expansion.

• DFG Programme: Priority Programmes
• Subproject of: SPP 1458: High Temperature Superconductivity in Iron Pnictides
• Participating Person: Dr. Yuri Koval