Tunable viscous layers in Corbino geometry using density junctions

TL;DR

This paper demonstrates how to create and control tunable viscous electron layers at density interfaces in a Corbino geometry, revealing their effects on magnetoresistance and potential for electronic device engineering.

Contribution

It introduces a method to produce and tune viscous layers in electron fluids at density junctions, supported by simulations and analytic models.

Findings

Tunable viscous layers can be formed by varying density ratios.

Viscous layers influence magnetoresistance depending on density distribution.

Varying density interfaces can suppress or enhance magnetoresistance.

Abstract

In sufficiently clean materials where electron-electron interactions are strong compared to momentum-relaxing scattering processes, electron transport resembles the flow of a viscous fluid. We study hydrodynamic electron transport across density interfaces (n-n junctions) in a 2DEG in the Corbino geometry. From numerical simulations in COMSOL using realistic parameters, we show that we can produce tunable viscous layers at the density interface by varying the density ratio of charge carriers. We quantitatively explain this observation with simple analytic expressions together with boundary conditions at the interface. We also show signatures of these viscous layers in the magnetoresistance. Breaking down viscous and ohmic contributions, we find that when outer radial region of the Corbino has higher charge density compared to the inner region, the viscous layers at the interface serve to suppress the magneto-resistance produced by momentum-relaxing scattering. Conversely, the magneto-resistance is enhanced when the inner region has higher density than the outer. Our results add to the repertoire of techniques for engineering viscous electron flows, which hold a promise for applications in future electronic devices.