Spin noise of localized electrons in CdTe/CdMgTe quantum well

TL;DR

This study uses spin noise spectroscopy to analyze the spin dynamics of localized electrons in a CdTe/CdMgTe quantum well, revealing unique relaxation behaviors and estimating donor concentration.

Contribution

It provides new insights into electron spin relaxation and dephasing mechanisms in quantum wells, distinguishing them from bulk materials, and offers a theoretical analysis of spin interactions.

Findings

Temperature activates spin-independent hopping, accelerating relaxation.

Contrasts with bulk CdTe where motional narrowing occurs.

Estimates donor concentration through spin noise analysis.

Abstract

The spin dynamics of localized electrons in bulk semiconductors is governed by the interplay of effective nuclear field fluctuations, spin exchange between electrons, and spin transitions into the conduction band. Using spin noise spectroscopy, we reveal this interplay for donor-bound electrons in a CdTe/CdMgTe quantum well and spectrally separate electron spin relaxation and dephasing in zero magnetic field. We identify a specific regime of the electron spin dynamics, where temperature-induced activation of spin-independent hopping leads to a monotonic acceleration of electron spin relaxation. This behavior contrasts with bulk CdTe crystals, where the motional narrowing effect is observed. We attribute this difference to the significantly larger inhomogeneous broadening of the donor-related trion resonance in our quantum well compared to bulk samples. The theoretical analysis of the spin noise power and the strength of the spin exchange interaction provides the estimation of the donor concentration in our unintentionally doped structure.