Exciton spin manipulation in inAs/GaAs quantum dots : Exchange interaction and magnetic field effects

• Published in: Physical review. B, Condensed matter and materials physics Vol. 71; no. 11; pp. 115334.1 - 115334.6
• Main Authors: SENES, M, URBASZEK, B, MARIE, X, AMAND, T, TRIBOLLET, J, BERNARDOT, F, TESTELIN, C, CHAMARRO, M, GERARD, J.-M
• Format: Journal Article
• Language: English
• Published: Ridge, NY American Physical Society 15-03-2005
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Exact sciences and technology; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Optical properties of low-dimensional, mesoscopic, and nanoscale materials and structures; Physics; Quantum dots; Polarization; Gallium arsenides; Excitons; Semiconductor materials; Quantum dots; Quantum beats; Photoluminescence; Magnetic field effects; Binary compounds; Time resolved spectra; Indium arsenides; Exchange interactions
• ISSN: 1098-0121; 1550-235X
• DOI: 10.1103/PhysRevB.71.115334

We report quantum beat phenomena between different polarization states in InAs quantum dots, observed in time-resolved photoluminescence and transient dichroism measurements. The polarization of the emitted light can be changed from linear to circular by applying a small magnetic field. Following quasiresonant excitation the electron and hole spin states remain stable during the exciton lifetime, independent of the applied magnetic field. We show that the exciton spin coherence is partially preserved in the energy relaxation process. These experiments enable us to measure the anisotropic exchange energy delta(Exy) and the exciton g factor. We find delta(Exy)30 µeV and g2.5 for the quantum dot excitons.