Growth Direction Dependence of the Electron Spin Dynamics in {111} GaAs Quantum Wells

TL;DR

This study investigates how the growth direction of {111} GaAs quantum wells influences electron spin dynamics, revealing that external electric fields can significantly extend spin lifetimes through spin relaxation mechanism suppression, with implications for spintronic device design.

Contribution

It demonstrates the dependence of electron spin lifetime enhancement on growth orientation and electric field direction in {111} GaAs quantum wells, highlighting the importance of growth direction in spintronic applications.

Findings

Spin lifetimes increase with external electric field application.

The effect depends on the substrate orientation: (111)A or (111)B.

Cancellation of Dresselhaus and Rashba effects extends spin coherence.

Abstract

The electron spin dynamics is studied by time-resolved Kerr rotation in GaAs/AlGaAs quantum wells embedded in a negatively doped-intrinsic-positively doped structures grown on (111)A or (111)B-oriented substrates. In both cases the spin lifetimes are significantly increased by applying an external electric field but this field has to point along the growth direction for structures grown on (111)A and opposite to it for the ones grown on (111)B. This extended electron spin lifetime is the result of the suppression of the D'yakonov-Perel spin relaxation mechanism [Sov. Phys. Solid State 13, 3023 (1972)] due to the cancellation effect of the internal Dresselhaus term [Phys. Rev. 100, 580 (1955)] with the external electric field induced Rashba one [J. Phys. C 17, 6039 (1984)], both governing the conduction band spin-orbit splitting. These results demonstrate the key role played by the growth direction in the design of spintronic devices.