Probing the viscosity of conduction electrons in metals
University of Geneva
1 or 2 semesters
An important property characterizing a liquid is its viscosity. Honey is for example very viscous, while water is rather fluid. Metals conduct electricity because the electrons also form a kind of liquid, so that electrical currents can flow around bends and obstacles just like water in a river. Hence electrical currents are actually currents of a charged liquid. What about the viscosity? Are electrons in a metal, plasmas or the corona of the sun like honey or like water ? To find out how viscous a liquid is, one has to shake it locally, and see how the rest is dragged along. According to theory the viscosity is a manifestation of correlated behavior of the electrons, and this should influence the reflectivity of infrared light at the surface of a metal, in the transmission through a conducting thin film, and peculiar oscillatory electric field patterns inside the material. It should be possible to measure these effects and tell how viscous the electrons really are. This is a new field, and experiments are only beginning. Van der Marel and collaborators are pioneers in this newly emerging field (see e.g. ""Electromagnetic properties of viscous charged fluids"" by D. Forcella, J. Zaanen, D. Valentinis, and D. van der Marel, Physical Review B 90, 035143 (2014)).
The project is also open for recently graduated undergraduate students who have not yet started their graduate programme.
The project will be available in the Fall and Spring semester.
Number of places available: 1 per semester.
- An introductory course in quantum mechanics is required previous to joining the lab.
Condensed Matter Physics.
In the treasure trove of quantum materials lurk possibilities beyond our wildest dreams. In recent years a worldwide quest for novel phases of matter has brought to light -and continues to do so- many novel states of matter emerging from interactions and correlated motion of electrons. Electron-electron interactions, combined with the laws of quantum mechanics, constitute one of the biggest theoretical challenges known in theoretical physics. Characterizing and understanding this new generation of electronic materials requires carefully executed experiments. These include advances in size reduction of scanning probe microscopes, novel optical techniques, X-ray, neutron, and photoelectron spectroscopy. These experimental techniques allow detailed mapping of the landscape of atoms, charge and spin and unveil the properties and functionalities of novel perspective materials. All these aspects form part of the research program at the Department of Quantum Matter Physics of the University of Geneva.