Spin transfer and coherence in coupled quantum wells

TL;DR

This study investigates spin dynamics in coupled quantum wells, revealing how electric field and barrier thickness influence coupling regimes, including independent, incoherent, and coherent spin transfer, governed by tunneling time, spin lifetime, and precession period.

Contribution

It demonstrates the dependence of spin transfer regimes on electric field, barrier thickness, and key timescales, providing new insights into spin coherence control in quantum well systems.

Findings

Identified three spin coupling regimes: independent, incoherent, and coherent.

Showed inter-well coupling depends on electric field and barrier thickness.

Linked coupling behavior to tunneling time, spin lifetime, and precession period.

Abstract

Spin dynamics of optically excited electrons confined in asymmetric coupled quantum wells are investigated through time resolved Faraday rotation experiments. The inter-well coupling is shown to depend on applied electric field and barrier thickness. We observe three coupling regimes: independent spin precession in isolated quantum wells, incoherent spin transfer between single-well states, and coherent spin transfer in a highly coupled system. Relative values of the inter-well tunneling time, the electron spin lifetime, and the Larmor precession period appear to govern this behavior.