3,080 research outputs found
Coherent spin dynamics of electrons and holes in semiconductor quantum wells and quantum dots under periodical optical excitation: resonant spin amplification versus spin mode-locking
The coherent spin dynamics of resident carriers, electrons and holes, in
semiconductor quantum structures is studied by periodical optical excitation
using short laser pulses and in an external magnetic field. The generation and
dephasing of spin polarization in an ensemble of carrier spins, for which the
relaxation time of individual spins exceeds the repetition period of the laser
pulses, are analyzed theoretically. Spin polarization accumulation is
manifested either as resonant spin amplification or as mode-locking of carrier
spin coherences. It is shown that both regimes have the same origin, while
their appearance is determined by the optical pump power and the spread of spin
precession frequencies in the ensemble
Radiative corrections to the magnetic-dipole transition amplitude in B-like ions
The one-electron quantum-electrodynamic corrections to the magnetic-dipole
transition amplitude between the fine-structure levels (1s^2 2s^2 2p) ^2P_3/2 -
^2P_1/2 in boronlike ions are calculated to all orders in (\alpha Z). The
results obtained serve for improving the theoretical accuracy of the lifetime
of the (1s^2 2s^2 2p) ^2P_3/2 level in boronlike argon
Time-resolved and continuous-wave optical spin pumping of semiconductor quantum wells
Experimental and theoretical studies of all-optical spin pump and probe of
resident electrons in CdTe/(Cd,Mg)Te semiconductor quantum wells are reported.
A two-color Hanle-MOKE technique (based on continuous-wave excitation) and
time-resolved Kerr rotation in the regime of resonant spin amplification (based
on pulsed excitation) provide a complementary measure of electron spin
relaxation time. Influence of electron localization on long-lived spin
coherence is examined by means of spectral and temperature dependencies.
Various scenarios of spin polarization generation (via the trion and exciton
states) are analyzed and difference between continuous-wave and pulsed
excitations is considered. Effects related to inhomogeneous distribution of
-factor and anisotropic spin relaxation time on measured quantities are
discussed.Comment: 26 pages, 19 figures, submitted to special issue on Optical
Orientation of Semiconductor Science and Technolog
- …