Zitterbewegung-mediated RKKY coupling in topological insulator thin films

TL;DR

This paper explores how Zitterbewegung influences RKKY coupling in topological insulator thin films, revealing anisotropic electron trajectories linked to topological phase transitions and potential experimental detection methods.

Contribution

It introduces a microscopic model connecting electron Zitterbewegung with RKKY interactions in TI thin films, highlighting control via film thickness and magnetic fields.

Findings

Electron trajectories are anisotropic and confined within characteristic regions.

Zitterbewegung occurs at the topological phase transition point.

Implications for electron-mediated RKKY coupling in TI systems.

Abstract

The dynamics of itinerant electrons in topological insulator (TI) thin films is investigated using a multi-band decomposition approach. We show that the electron trajectory in the 2D film is anisotropic and confined within a characteristic region. Remarkably, the confinement and anisotropy of the electron trajectory are associated with the topological phase transition of the TI system, which can be controlled by tuning the film thickness and/or applying an in-plane magnetic field. Moreover, persistent electron wavepacket oscillation can be achieved in the TI thin film system at the phase transition point, which may assist in the experimental detection of the jitter motion (Zitterbewegung). The implications of the microscopic picture of electron motion in explaining other transport-related effects, e.g., electron-mediated RKKY coupling in the TI thin film system, are also discussed.