A spintronic analog of the Landauer residual resistivity dipole on the surface of a disordered topological insulator

TL;DR

This paper demonstrates a spintronic analog of the Landauer residual resistivity dipole on disordered topological insulator surfaces, revealing spin imbalance effects, magnetic field generation, and potential electromagnetic radiation from scatterers.

Contribution

It introduces a novel spintronic residual resistivity dipole concept on topological insulator surfaces, linking spin imbalance, magnetic fields, and electromagnetic radiation to scattering phenomena.

Findings

Spin imbalance forms around scatterers on TI surfaces.

Magnetic fields are generated and cause spin precession.

Scatterers can act as miniature antennas emitting electromagnetic waves.

Abstract

The Landauer "residual resistivity dipole" is a well-known concept in electron transport through a disordered medium. It is formed when a defect/scatterer reflects an impinging electron causing negative charges to build up on one side of the scatterer and positive charges on the other. This results in the formation of a microscopic electric dipole that affects the resistivity of the medium. Here, we show that an equivalent entity forms in spin polarized electron transport through the surface of a disordered topological insulator (TI). When electrons reflect from a scatterer on the TI surface, a spin imbalance forms around the scatterer, resulting in a spin current that flows either in the same or the opposite direction as the injected spin current and hence either increases or decreases the spin resistivity. It also destroys spin-momentum locking and produces a magnetic field around the scatterer. The latter will cause transiting spins to precess as they pass the scatterer, thereby radiating electromagnetic waves and implementing an oscillator. If an alternating current is passed through the TI instead of a static current, the magnetic field will oscillate with the frequency of the current and radiate electromagnetic waves of the same frequency, thus making the scatterer act as a miniature antenna.