Unconventional transport in low-density two-dimensional Rashba systems

Abstract

Rashba spin-orbit coupling appears in 2D systems lacking inversion symmetry, and causes the spinsplitting of otherwise degenerate energy bands into an upper and lower helicity band. In this paper, we explore how impurity scattering affects transport in the ultra-low density regime where electrons are confined to the lower helicity band. A previous study has investigated the conductivity in this regime using a treatment in the first Born approximation. In this work, we use the full T -matrix to uncover new features of the conductivity. We first compute the conductivity within a semiclassical Boltzmann framework and show that it exhibits an unconventional density dependence due to the unusual features of the group velocity in the single particle dispersion, as well as quantized plateaus as a function of the logarithm of the electron density. We support this with a calculation using the Kubo formula and find that these plateaus persist in the full quantum theory. We suggest that this quantization may be seen in a pump-probe experiment.

Two‐Particle Scattering and Resistivity of Rashba Electron Gas

“…The corresponding current density is given by Eq. (12) with v µ , p ±µ , and Φ ±µ taken (20) and has the temperature dependence T 4 ln |E F /T |. A similar temperature dependence was recently obtained for the relaxation rate of higher-order odd angular harmonics of electron distribution in 2D systems with parabolic spectrum due to electron-electron collisions.…”

“…This equation is easily solved for C ee µ and the correction to the current is calculated using Eq. (12). Below the Dirac point, it equals…”

“…This coupling spin-splits the dispersion curve into the upper and lower helicity bands. It was found that in the low-density regime when only the lower band is filled, the impurity-related resistivity exhibits an unconventional electron-density dependence [11][12][13] . Apparently, this system is not Galilean-invariant and is described at the same time by a minimum number of independent parameters.…”

Electron-electron scattering and transport properties of spin-orbit coupled electron gas

“…Apart from this, they possess a nontrivial structure of energy bands, which makes their charge-and heattransport properties an interesting subject of research. So far, the main attention was focused on 2D SOC systems with purely elastic scattering [2][3][4][5][6] . In particular, it was found that the impurity-related resistivity exhibits an unconventional dependence on the electron density 2,4 .…”

“…So far, the main attention was focused on 2D SOC systems with purely elastic scattering [2][3][4][5][6] . In particular, it was found that the impurity-related resistivity exhibits an unconventional dependence on the electron density 2,4 . Far less attention was given to the effects of inelastic scattering.…”