Long-lived electron spins in a modulation doped (100) GaAs quantum well

TL;DR

This study measures long electron spin lifetimes exceeding one microsecond in a GaAs quantum well, revealing nuclear polarization effects and multiple localized electron states, advancing understanding of spin dynamics in semiconductor nanostructures.

Contribution

It provides the first measurement of T1 spin lifetimes over one microsecond in a modulation-doped GaAs quantum well at low temperature and high magnetic field.

Findings

T1 spin lifetimes >1 microsecond at 1.5 K and 5.5 T

Nuclear polarization effects observed and mitigated by NMR

Evidence of two distinct localized electron states

Abstract

We have measured T1 spin lifetimes of a 14 nm modulation-doped (100) GaAs quantum well using a time-resolved pump-probe Kerr rotation technique. The quantum well was selected by tuning the wavelength of the probe laser. T1 lifetimes in excess of 1 microsecond were measured at 1.5 K and 5.5 T, exceeding the typical T2* lifetimes that have been measured in GaAs and II-VI quantum wells by orders of magnitude. We observed effects from nuclear polarization, which were largely removable by simultaneous nuclear magnetic resonance, along with two distinct lifetimes under some conditions that likely result from probing two differently-localized subsets of electrons.