Max Planck Research Group PUMAS -
Physics of Unconventional Metals and Superconductors
Unconventional metals show a number of novel states of matter at low temperature that cannot be understood within an established quantum mechanical treatment. Examples are unusual ordered phases, non-Fermi-liquid behavior and unconventional superconductivity. It is the interaction (correlation) between the electrons, which makes these interesting quantum many body states emerge.
Our group strives for further understanding of these novel states of matter by experimental investigations at very low temperature and under high magnetic field and high pressure. Particularly, we are trying to understand the electronic behavior in novel states of matter through a direct detection of the Fermi surface via quantum oscillations, a fundamental “fingerprint” of a material.
This powerful technique implies the challenge of creating a very low noise environment and requiring extremely pure crystals. It gives information on the 3D Fermi surface topology and anisotropy, quasiparticle effective masses, quasiparticle scattering and magnetic interactions.
Quantum oscillation measurements are also carried out under high pressure. Pressure is a parameter that allows changing the lattice constants and therefore the interaction of the electrons. It is a clean tuning parameter as opposed to chemical substitution where impurities are introduced to the lattice. By tuning the ground states with pressure, we are able to study the interplay and competition of their according order parameters.
This group is independent from the other departments within the Max Planck Institute but works in strong collaboration with them and has access to the extraordinary infrastructure of the institute.