Agenda

In this talk, I will discuss recent advances in scanning tunneling microscopy and spectroscopy at magnetic fields of 20 T. First, I will present improvements in the instrumentation that have allowed to build compact microscopes with which we have been able to make measurements at 20 T. I will then discuss results obtained in iron pnictide superconductors. In particular, I will focus on the recent family of CaKNi4As4 materials, which has very high critical temperatures (up to 38 K) and presents isotropic two gap superconductivity. I will show measurements of the properties of the vortex lattice and of the bandstructure, the latter obtained using quasiparticle interference. I will further present recent results in the vortex phase of other iron pnictide superconductors.