Optically-detected long-lived spin coherence in multilayer systems: Double and triple quantum wells

TL;DR

This study demonstrates long-lived spin coherence in multilayer quantum wells, revealing spin lifetimes up to 25 ns, which are limited by spin hopping and g-factor spread, using optical Kerr rotation and spin amplification techniques.

Contribution

It provides the first detailed measurement of long spin lifetimes in dense multilayer quantum wells beyond the metal-insulator transition.

Findings

Double quantum wells exhibit 6.25 ns spin lifetime at 5 K.

Triple quantum wells show spin lifetime exceeding 25 ns at 8 K.

Long spin coherence is limited by Dyakonov-Perel mechanism and spin hopping.

Abstract

In this contribution, we investigated the spin coherence of high-mobility dense two-dimensional electron gases confined in multilayer systems. The dynamics of optically-induced spin polarization was experimentally studied employing the time-resolved Kerr rotation and resonant spin amplification techniques. For both the double and triple quantum wells doped beyond the metal-insulator transition, where the spin coherence is greatly suppressed, we found remarkably long spin lifetimes limited by the Dyakonov-Perel mechanism and spin hopping process between the donor sites as well as the spread of ensemble g-factor. The double quantum well structure yields a spin lifetime of 6.25 ns at T = 5 K while the triple quantum well shows a spin lifetime exceeding 25 ns at T = 8 K.