3,009 research outputs found
The Ferromagnetism in the Vicinity of Lifshitz Topological Transitions
We show that the critical temperature of a ferromagnetic phase transition in
a quasi-two-dimensional hole gas confined in a diluted magnetic semiconductor
quantum well strongly depends on the hole chemical potential and hole density.
The significant variations of the the Curie temperature occur close to the
Lifshitz topological transition points where the hole Fermi surface acquires
additional components of topological connectivity due to the filling of excited
size-quantization subbands. The model calculations demonstrate that the Curie
temperature can be doubled by a small variation of the gate voltage for the
CdMnTe/CdMgTe quantum well based device
Spin noise spectroscopy of a single-quantum-well microcavity
We report on the first experimental observation of spin noise in a single
semiconductor quantum well embedded into a microcavity. The great
cavity-enhanced sensitivity to fluctuations of optical anisotropy has allowed
us to measure the Kerr rotation and ellipticity noise spectra in the strong
coupling regime. The spin noise spectra clearly show two resonant features: a
conventional magneto-resonant component shifting towards higher frequencies
with magnetic field and an unusual "nonmagnetic" component centered at zero
frequency and getting suppressed with increasing magnetic field. We attribute
the first of them to the Larmor precession of free electron spins, while the
second one being presumably due to hyperfine electron-nuclei spin interactions.Comment: 5 pages, 6 figures + supplement (4 pages, 1 figure
QED calculation of the 2p1/2-2s and 2p3/2-2s transition energies and the ground-state hyperfine splitting in lithiumlike scandium
We present the most accurate up-to-date theoretical values of the
{2p_{1/2}}-{2s} and {2p_{3/2}}-{2s} transition energies and the ground-state
hyperfine splitting in . All two- and three-electron
contributions to the energy values up to the two-photon level are treated in
the framework of bound-state QED without \aZ-expansion. The interelectronic
interaction beyond the two-photon level is taken into account by means of the
large-scale configuration-interaction Dirac-Fock-Sturm (CI-DFS) method. The
relativistic recoil correction is calculated with many-electron wave functions
in order to take into account the electron-correlation effect. The accuracy of
the transition energy values is improved by a factor of five compared to the
previous calculations. The CI-DFS calculation of interelectronic-interaction
effects and the evaluation of the QED correction in an effective screening
potential provide significant improvement for the hyperfine splitting. The
results obtained are in a good agreement with recently published experimental
data.Comment: 10 pages, 2 table
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