Tailoring multilayer quantum wells for spin devices

TL;DR

This study investigates electron spin dynamics in multilayer GaAs/AlGaAs quantum wells, revealing long spin coherence times and mechanisms influencing spin relaxation, with implications for spintronic device development.

Contribution

It demonstrates how wave function engineering in multilayer quantum wells can significantly enhance spin coherence times and control spin relaxation mechanisms.

Findings

Long spin coherence time T2* > 13 ns in doped multilayer wells

Dyakonov-Perel mechanism dominates spin relaxation, affected by g-factor inhomogeneity

Spin relaxation anisotropy enhances T2* along the growth direction

Abstract

The electron spin dynamics in multilayer GaAs/AlGaAs quantum wells, containing high-mobility dense two-dimensional electron gases, have been studied using time-resolved Kerr rotation and resonant spin amplification techniques. The electron spin dynamics was regulated through the wave function engineering and quantum confinement in multilayer quantum wells. We observed the spin coherence with a remarkably long dephasing time T2* > 13 ns for the structure doped beyond metal-insulator transition. Dyakonov-Perel spin relaxation mechanism, as well as the inhomogeneity of electron g-factor, was suggested as the major limiting factors for the spin coherence time. In the metallic regime, we found that the electron-electron collisions become dominant over microscopic scattering on the electron spin relaxation with the Dyakonov-Perel mechanism. Furthermore, the data analysis indicated that in our structure, due to the spin relaxation anisotropy, Dyakonov-Perel spin relaxation mechanism is efficient for the spins oriented in-plane and suppressed along the quantum well growth direction resulting in the enhancement of T2*. Our findings, namely, long-lived spin coherence persisting up to about room temperature, spin polarization decay time with and without a magnetic field, the spin-orbit field, single electron relaxation time, transport scattering time, and the electron-electron Coulomb scattering time highlight the attractiveness of n-doped multilayer systems for spin devices.