Enhancing Spin Diffusion in GaAs Quantum Wells: The Role of Electron Density and Channel Width

TL;DR

This paper investigates how electron density and channel width affect spin diffusion in GaAs quantum wells, demonstrating that reducing channel width and electron density enhances spin transport, with implications for spintronic device design.

Contribution

It provides experimental and theoretical insights into optimizing spin diffusion by tuning electron density and channel geometry in GaAs quantum wells.

Findings

Spin diffusion coefficient increases with narrower channels.

Lower electron density amplifies spin diffusion enhancement.

Theoretical model explains inhomogeneities due to electron-density variations.

Abstract

This study explores the relationship between spin diffusion, spin lifetime, electron density and lateral spatial confinement in two-dimensional electron gases hosted in GaAs quantum wells. Using time-resolved magneto-optical Kerr effect microscopy, we analyze how Hall-bar channel width and back-gate voltage modulation influence spin dynamics. The results reveal that the spin diffusion coefficient increases with reduced channel widths, a trend further amplified at lower electron concentrations achieved via back-gate voltages, where it increases up to 150% for the narrowest channels. The developed theoretical model confirms the spatial inhomogeneities in the spin diffusion as arising from electron-density variations within the channels. The results underscore the importance of tuning electron density and spatial geometry to optimize spin transport and coherence, providing valuable design considerations for spintronic devices where efficient spin manipulation is crucial.