title: Evidence for the light hole in GaAs/AlGaAs quantum wells from optically-pumped NMR and Hanle curve measurements.
abstract: Optically-pumped (69)Ga NMR (OPNMR) and optically-detected measurements of polarized photoluminescence (Hanle curves) show a characteristic feature at the light hole-to-conduction band transition in a GaAs/AlxGa1-xAs multiple quantum well sample. OPNMR data are often depicted as a "profile" of the OPNMR integrated signal intensity plotted versus optical pumping photon energy. What is notable is the inversion of the sign of the measured (69)Ga OPNMR signals when optically pumping this light hole-to-conduction band energy in OPNMR profiles at multiple external magnetic fields (B0=4.7T and 3T) for both σ(+) and σ(-) irradiation. Measurements of Hanle curves at B0=0.5T of the same sample exhibit similar phase inversion behavior of the Hanle curves at the photon energy for light hole excitation. The zero-field value of the light-hole state in the quantum well can be predicted for the quantum well structure using the positions of each of these signal-inversion features, and the spin splitting term in the equation for the transition energy yields consistent values at 3 magnetic fields for the excitonic g-factor (g(ex)). This study demonstrates the application of OPNMR and optical measurements of the photoluminescence to detect the light hole transition in semiconductors.
authors.affiliation: Department of Chemistry, Washington University in St. Louis, St. Louis, MO 63130, United States.
authors.forename: Erika L
authors.initials: EL
authors.lastname: Sesti
authors.affiliation: Fakultät Physik, Technische Universität Dortmund, 44221 Dortmund, Germany.
authors.forename: Wieland A
authors.initials: WA
authors.lastname: Worthoff
authors.affiliation: Department of Chemistry, Washington University in St. Louis, St. Louis, MO 63130, United States.
authors.forename: Dustin D
authors.initials: DD
authors.lastname: Wheeler
authors.affiliation: Fakultät Physik, Technische Universität Dortmund, 44221 Dortmund, Germany.
authors.forename: Dieter
authors.initials: D
authors.lastname: Suter
authors.affiliation: Department of Chemistry, Washington University in St. Louis, St. Louis, MO 63130, United States. Electronic address: hayes@wustl.edu.
authors.forename: Sophia E
authors.initials: SE
authors.lastname: Hayes
keywords: (69)Ga NMR; GaAs/AlGaAs quantum well; Hanle curve; Light hole; OPNMR; Optically-pumped NMR