Berlin 2018 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 95: Cold Atomic Gases, Superfluids, Quantum Fluids and Solids

TT 95.10: Vortrag

Donnerstag, 15. März 2018, 17:30–17:45, HFT-FT 131

AC conductivity of a two-dimensional electronic fluid — Roderich Moessner, Piotr Surowka, and •Piotr Witkowski — Max-Planck-Institut für Physik komplexer Systeme, Nöthnitzer Str. 38, 01187 Dresden, Germany

Motivated by experiments on a hydrodynamic regime in electron transport, we study the effect of an oscillating electric field in such a setting. We consider a long two-dimensional channel of, whose geometrical simplicity allows an analytical study as well as hopefully permitting experimental realisation. We find two, distinctive regimes: a quasi-static flow, and a boundary layer type behaviour. The latter includes a splitting of the location of maximal flow velocity from the centre towards the edges of the boundary layer, an an increasingly reactive nature of the response, with the phase shift of the response varying across the channel. In which regime we are, depends on dimensionless combination of channel width, viscosity and forcing frequency, similar to the Reynolds number. The scaling of the total optical conductance with channel width differs between the two regimes, while its frequency dependence resembles a Drude form throughout, even in the complete absence of ohmic heating, against which, at the same time, our results are stable. Current estimates for transport coefficients in graphene and delafossites suggest that the boundary layer regime should be experimentally accessible.