Spin polarization of two-dimensional electrons in GaAs quantum wells around Landau level filling v=1 from NMR measurements of gallium nuclei

S. Melinte, N. Freytag, M. Horvatić, C. Berthier, L. P. Lévy, V. Bayot, Mansour Shayegan

Research output: Contribution to journalArticle

15 Scopus citations

Abstract

A nuclear magnetic resonance (NMR) study has been carried out on a GaAs/Al0.3Ga0.7As multiple-quantum-well sample, containing two-dimensional (2D) electron layers, in the quantum Hall regime. The spin polarization P of 2D electrons is determined from the hyperfine shift of 69.71Ga nuclei, measured by standard pulsed NMR. We have used the tilted-magnetic field technique to investigate the effect of an increasing Zeeman energy on P around Landau level filling factor v=1. Mostly on the basis of measurements performed at B=17 T and T=1.5 K, we conjecture that in the high-B and low-T limit, P(v) follows the predictions of the noninteracting-electron model. The low-temperature P(v=1) is found to be far below the expected full polarization, and the observed nuclear spin-lattice relaxation rate is not reduced, in contrast to the observations by optically pumped NMR. The two techniques obtain different results only close to v=1, and the reason why remains unclear; simple explanation in terms of the nonuniform electron density does not seem satisfactory.

Original languageEnglish (US)
Article number085327
Pages (from-to)853271-853279
Number of pages9
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume64
Issue number8
StatePublished - Aug 15 2001
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

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