Delocalization of charge and current in a chiral quasiparticle wave-packet

TL;DR

This paper studies the internal structure of chiral quasi-particle wave packets in 2D electron systems with Rashba spin-orbit coupling, revealing charge delocalization effects influenced by interaction strength and external tuning.

Contribution

It introduces a detailed analysis of charge and current distributions in chiral quasi-particle wave packets, highlighting the tunable delocalization effects due to Rashba spin-orbit coupling.

Findings

Charge within the wave packet is less than the bare charge and some resides at the boundary.

Delocalized charge inversely proportional to Fermi velocity for weak RSOC.

Charge and current densities exhibit anisotropic $r^{-2}$ tails.

Abstract

A chiral quasi-particle wave packet (c-QPWP) is defined as a conventional superposition of chiral quasi-particle states corresponding to an interacting electron system in two dimensions (2D) in the presence of Rashba spin-orbit coupling (RSOC). I investigate its internal structure via studying the charge and the current densities within the first order perturbation in the electron-electron interaction. It is found that the c-QPWP contains a localized charge which is less than the magnitude of the bare charge and the remaining charge resides at the system boundary. The amount of charge delocalized turns out to be inversely proportional to the degenerate Fermi velocity $v_0 ( = \sqrt{\alpha^2 + 2\mu / m})$ when RSOC (with strength $\alpha$) is weak, and therefore externally tunable. For strong RSOC, the magnitudes of both the delocalized charge and the current further strongly depend on the direction of propagation of the wave packet. Both the charge and the current densities consist of an anisotropic $r^{-2}$ tail away from the centre of the wave packet. Possible implications of such delocalizations in real systems corresponding to 2D semiconductor heterostructure are also discussed within the context of particle injection experiments.