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Spin Orientation (spin + orientation)

Distribution by Scientific Domains
Physics and Astronomy100%

Selected Abstracts

Spin orientation of excitons, trions and tetraons in charge tunable InP quantum dots

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 1 2009
Yasuaki Masumoto
Abstract In the longitudinal magnetic field, photoluminescence (PL) polarization in InP quantum dots (QDs) dramatically changed depending on the number of doped electrons. Under linearly polarized excitation, PL polarizes resonantly at two magnetic fields where bright and dark excitons anticross each other in neutral QDs. On the other hand, PL polarization monotonously increases with the increase of longitudinal magnetic field in one- and two-electron doped QDs, where thermal spin orientation of a photoexcited hole determines the PL polarization of a trion and a tetraon. At low temperatures, however, the electron-hole exchange interaction reduces the thermal spin orientation of holes. In two-electron doped QDs, the anisotropic electron-hole exchange interaction gives small structure in the magnetic-field-dependent circular polarization at the low field region. Time-resolved circular polarization clearly shows the dynamical spin polarization process in charged QDs in the longitudinal magnetic field. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Characteristic magnetic length-scales in Vitroperm , Combining Kerr microscopy and small-angle neutron scattering

PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 15 2004
A. Grob
Abstract We present a study of the magnetic-field dependence of the magnetic microstructure of the nanocrystalline soft magnet Vitroperm (Fe73Si16B7Nb3Cu1), which was treated so as to exhibit a macroscopic magnetic anisotropy. The samples were analysed using Kerr microscopy and small-angle neutron scattering (SANS). As the applied magnetic field is decreased starting from saturation, we find that two processes occur independently: the formation of a domain structure with the net magnetisation of the domains aligned along the macroscopic easy axis and the increase in magnitude of static, nanometer-scale fluctuations of the spin orientation. The domain structure observations from Kerr microscopy are in excellent agreement with the results of the SANS experiments. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Optical spin orientation of a single manganese atom

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 6 2010
C. Le Gall
Abstract An optical spin orientation is achieved for a Mn atom localized in a semiconductor quantum dot using quasiresonant excitation at zero magnetic field. Optically created spin polarized carriers generate an energy splitting of the Mn spin and enable magnetic moment orientation controlled by the photon helicity and energy. The dynamics and the magnetic field dependence of the optical pumping mechanism shows that the spin lifetime of an isolated Mn atom at zero magnetic field is controlled by a magnetic anisotropy induced by the built-in strain in the quantum dots. Relaxation times exceeding the micro-second range are measured (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Spin orientation of excitons, trions and tetraons in charge tunable InP quantum dots

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 1 2009
Yasuaki Masumoto
Abstract In the longitudinal magnetic field, photoluminescence (PL) polarization in InP quantum dots (QDs) dramatically changed depending on the number of doped electrons. Under linearly polarized excitation, PL polarizes resonantly at two magnetic fields where bright and dark excitons anticross each other in neutral QDs. On the other hand, PL polarization monotonously increases with the increase of longitudinal magnetic field in one- and two-electron doped QDs, where thermal spin orientation of a photoexcited hole determines the PL polarization of a trion and a tetraon. At low temperatures, however, the electron-hole exchange interaction reduces the thermal spin orientation of holes. In two-electron doped QDs, the anisotropic electron-hole exchange interaction gives small structure in the magnetic-field-dependent circular polarization at the low field region. Time-resolved circular polarization clearly shows the dynamical spin polarization process in charged QDs in the longitudinal magnetic field. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]