Strongly correlated materials exhibit a plethora of fascinating phenomena, all the way from colossal magnetoresistance to unconventional superconductivity and quantum criticality, to just name a few. Many of these phenomena are not yet fully understood. In order to gain further insight comprehensive investigations of thermodynamic and transport properties of these materials, specifically at low temperatures, are called for.
We have set up Scanning Tunneling Microscopy (STM) which is an established powerful tool to investigate the electronic structure of materials. In an effort to optimize sensitivity for the materials and phenomena in quest we can conduct STM in UHV, down to 310 mK and in applied magnetic fields of up to 12 T. With these tools, we primarily investigate heavy fermion materials, Kondo insulators and iron based superconductors.
At present we are extending these measurements to investigate the fate of the Kondo quasi- particles upon approach of the quantum critical point in YbRh2Si2. Moreover, we currently explore the nature of the Kondo interaction in Sm hexaboride, in particular in relation to the proposed topological surface state in this material. We also study the polaron formation in EuB6 as well as the formation of the superconducting gap in FeSe.
Specifically for the latter projects, we invite students to actively participate in our ongoing research on an eight months visiting basis. Interest, or even experience, in STM, UHV and/or low temperature technology is highly welcome. In order to gain insight in using our STMs, students would initially be guided by experienced postdoctoral researchers on a daily basis. In a next step, the topography of in situ cleaved samples will be investigated particularly in the case of new materials because well-cleaved surfaces are a prerequisite for any sophisticated spectroscopic study. Students will also gain some insight into routine sample characterization (e.g. by PPMS and MPMS measurements) and thin film growth.
Dr. Steffen Wirth,
Max Planck Institute for Chemical Physics of Solids, Dresden, Germany