Regensburg 2016 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 7: Transport I: Electronic and thermal transport
MM 7.2: Vortrag
Montag, 7. März 2016, 11:45–12:00, H53
Evidence for hydrodynamic electron flow in PdCoO2 — Philip Moll1,2, Pallavi Kushwaha3, •Nabhanila Nandi3, Burkhard Schmidt3, and Andrew Mackenzie3,4 — 1Laboratory for Solid State Physics, ETH Zurich, Switzerland — 2Department of Physics, University of California, Berkeley, California 94720, USA — 3Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Straße 40, 01187 Dresden, Germany — 4Scottish Universities Physics Alliance, School of Physics and Astronomy, University of St. Andrews, St. Andrews KY16 9SS, United Kingdom
The electrical resistance is conventionally determined by the momentum-relaxing scattering of electrons by the host solid and its excitations. Hydrodynamic fluid flow through channels, in contrast, is determined by geometrical factors, boundary scattering and the viscosity of the fluid, which is governed by momentum-conserving internal collisions. A longstanding question in the physics of solids has been whether the viscosity of the electron fluid plays an observable role in determiningthe resistance. At first sight this seems unlikely, because in almost all known materials the rate of momentum-relaxing collisions dominates that of the momentum-conserving ones that give the viscous term. Here, we show this is not always the case. We report experimental evidence that the resistance of restricted channels of the ultra-pure two-dimensional metal PdCoO2 has a large viscous contribution. Comparison with theory allows an estimate of the electronic viscosity to be similar to water at room temperature or liquid nitrogen at 75 K.