Magnetotransport of tomographic electrons in a channel

Abstract

Hydrodynamics is a new paradigm of electron transport in high-mobility devices, where frequent electron collisions give rise to a collective electron flow profile. However, conventional descriptions of these flows, which are based on the fluid equations for a classical gas extended to include impurity scattering, do not account for the distinct collisional relaxation in quantum-mechanical systems. In particular, by dint of Pauli blocking even modes of the distribution function relax over significantly shorter length scales than odd modes (dubbed the ``tomographic'' effect). We establish an analytical description of tomographic electron flow in a channel, and find four new distinguishing features: (i) Non-equilibrium effects from the boundaries penetrate significantly deeper into the flow domain; (ii) an additional velocity slip condition leads to a significant increase in the channel conductance; (iii) bulk rarefaction corrections decrease the curvature of the velocity profile in the channel center; and (iv) all these anomalous transport effects are rapidly suppressed with magnetic fields. The latter effect leads to a non-monotonic magneto-conductance, which can be used to measure both the even- and odd-mode mean free paths. Our asymptotic results unveil the underlying physics of tomographic flows and provide an alternative to numerical solutions of the Fermi-liquid equations.