Abstract
The electronic analog of the Poiseuille flow is the transport in a narrow channel with disordered edges that scatter electrons in a diffuse way. In the hydrodynamic regime, the resistivity decreases with temperature, referred to as the Gurzhi effect, distinct from conventional Ohmic behaviour. We studied experimentally an electronic analog of the Stokes flow around a disc immersed in a two-dimensional viscous liquid. The circle obstacle results in an additive contribution to resistivity. If specular boundary conditions apply, it is no longer possible to detect Poiseuille type flow and the Gurzhi effect. However, in flow through a channel with a circular obstacle, the resistivity decreases with temperature. By tuning the temperature, we observed the transport signatures of the ballistic and hydrodynamic regimes on the length scale of disc size. Our experimental results confirm theoretical predictions.
Highlights
We studied experimentally an electronic analog of the Stokes flow around a disc immersed in a two-dimensional viscous liquid
By tuning the temperature in a wide interval1.5 < T < 70 K, we show that obstacle resistance Robst exhibits a drop as temperature increases, in consistence with predictions for the ballistic and hydrodynamic regimes
We have studied an electronic analog of the Stokes flow around the obstacle in a two-dimensional system in high quality GaAs quantum wells
Summary
The samples were grown by molecular beam epitaxy method. Our samples are high-quality, GaAs quantum wells with a width of 14 nm with electron density ns = 6 × 1011 cm−2 and a mobility of μ = 2.5 × 106 cm2/Vs at T = 1.4 K. Our giant negative magnetoresitance strongly depends on temperature and can be successfully described within a hydrodynamic framework[15] in wide temperature range, in contrast to the T-independent peak observed in paper[29] Even though both ballistic and hydrodynamic contribution are important at low temperature, at high temperature, the viscosity effect becomes dominant, and all our conclusion can be applied well to the samples with and without obstacle. The difference between rates 1/τ2,ee(T) for obstacle and reference samples can be attributed to uncertainty in the determination of the Lorentz curve width due to the satellite ballistic peak. In contrast obstacle resistance shows dρobst/dT < 0 in the same temperature region
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