Magnetic-field dependence of exciton spin relaxation in GaAs/AlxGa1xAs quantum wells

R. T. Harley and M. J. Snelling
Phys. Rev. B 53, 9561 – Published 15 April 1996
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Abstract

The magnetic-field dependence of spin relaxation of heavy-hole excitons in GaAs/AlxGa1xAs quantum wells is investigated at low temperatures. The variation of circular polarization of cw photoluminescence is modeled using steady-state solutions of rate equations describing the population dynamics of the exciton spin levels. Transitions between the levels are assumed to proceed via one-phonon ‘‘direct’’ processes, as well as zero-phonon processes when the levels are degenerate. Estimates of the exciton, hole, and electron spin-relaxation rates in units of the exciton population decay rate are obtained from least-squares fitting. We conclude that the exchange-driven exciton spin relaxation, involving simultaneous electron and hole spin flip, which dominates over hole or electron spin flips in zero field, is greatly reduced by a small applied field, which causes a Zeeman splitting and so suppresses the zero-phonon transitions. Level crossing signals in the data also show an enhancement of relaxation via zero-phonon hole spin flip when the Zeeman energy cancels the exchange energy. © 1996 The American Physical Society.

  • Received 6 November 1995

DOI:https://doi.org/10.1103/PhysRevB.53.9561

©1996 American Physical Society

Authors & Affiliations

R. T. Harley

  • Physics Department, The University of Southampton, Southampton, SO17 1BJ, United Kingdom

M. J. Snelling

  • Clarendon Laboratory, Parks Road, Oxford, United Kingdom

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Vol. 53, Iss. 15 — 15 April 1996

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