Scanning Tunneling Spectoscopy of Iron Pnictides

• Applicant: Professor Dr. Christian Hemker-Heß
• Subject Area: Experimental Condensed Matter Physics
• Term: from 2013 to 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 237721007

The aim of this project is to investigate the superconducting order parameter and the electronic structure of iron-arsenide superconductors by high-resolution scanning tunneling microscopy and spectroscopy (STM/STS) at low temperatures (down to 300 mK). For our investigations, we will use doped LiFeAs and NaFeAs single crystals. These materials exhibit an interesting interplay of magnetic and unconventional superconducting phases in the ground state, which is a generic feature of the physics of the iron pnictides. From our measurements we seek specific information about the electronic structure and the superconducting order parameter: i) We will measure the quasiparticle interference, that results from the quasiparticle scattering off natural and doped impurities and which contains phase sensitive information, in various magnetic fields. ii) We will measure and compare the densities of states at impurity sites and that of a clean surface area, from which we expect specific information about the pair-breaking effect and impurity bound-states of various impurity types. iii) We will apply spin-polarized STM (SP-STM) on individual defects and on clean surface areas in order to reveal the nature (magnetic or non-magnetic) of the observed defects and of possible magnetically ordered regions.

• DFG Programme: Priority Programmes
• Subproject of: SPP 1458: High Temperature Superconductivity in Iron Pnictides