Effects of a longitudinal magnetic field on spin injection and detection in InAs/GaAs quantum dot structures
2012 (English)In: Journal of Physics: Condensed Matter, ISSN 0953-8984, E-ISSN 1361-648X, Vol. 24, no 14, 145304- p.Article in journal (Refereed) Published
Effects of a longitudinal magnetic field on optical spin injection and detection in InAs/GaAs quantum dot (QD) structures are investigated by optical orientation spectroscopy. An increase in optical and spin polarization of the QDs is observed with increasing magnetic field in the range of 0-2 T, and is attributed to suppression of exciton spin depolarization within the QDs that is promoted by hyperfine interaction and anisotropic electron-hole exchange interaction. This leads to a corresponding enhancement in spin detection efficiency of the QDs by a factor of up to 2.5. At higher magnetic fields when these spin depolarization processes are quenched, electron spin polarization in anisotropic QD structures (such as double QDs that are preferably aligned along a specific crystallographic axis) still exhibits rather strong field dependence under non-resonant excitation. In contrast, such field dependence is practically absent in more "isotropic" QD structures (e.g. single QDs). We attribute the observed effect to stronger electron spin relaxation in the spin injectors (i.e. wetting layer and GaAs barriers) of the lower-symmetry QD structures, which also explains the lower spin injection efficiency observed in these structures.
Place, publisher, year, edition, pages
2012. Vol. 24, no 14, 145304- p.
Natural Sciences Condensed Matter Physics
IdentifiersURN: urn:nbn:se:liu:diva-74672DOI: 10.1088/0953-8984/24/14/145304ISI: 000302120500007OAI: oai:DiVA.org:liu-74672DiVA: diva2:490058
funding agencies|Swedish Research Council||2012-02-032012-02-032013-10-02Bibliographically approved