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Energy Dispersions (energy + dispersion)

Distribution by Scientific Domains
Physics and Astronomy100%

Selected Abstracts

The low-energy electronic properties of graphene ribbons in spatially modulated magnetic fields

PHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 12 2008
J. Y. Wu
Abstract The low energy magnetoelectronic structures for a nanographene ribbon under modulated magnetic fields are investigated through the Peierls tight-binding model. They are dominated by the field strength, period, phase, the ribbon width, and edge structure. The modulated magnetic field could add state degeneracy, modify energy dispersions, alter subband spacings, affect carrier-density distributions, create additional band-edge states, and extend the partial flat bands. The main features of energy bands are directly reflected in density of states, such as the position, the height, the structure, and the number of the prominent peaks. These results are compared with a zigzag ribbon under a uniform magnetic field. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Zero dimensional exciton-polaritons

PHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 10 2006
A. Baas
The cover picture from the article [1] shows, in the left parts of the three diagrams, the measured photoluminescence intensity as a function of energy and emission angle for a 3 ,m (left diagram), 9 ,m (middle diagram) and 19 ,m-diameter quasi-circular mesa (right diagram). The white lines are the energy dispersions of 2D polariton modes. For clarity, intensities above 1485 meV have been multiplied by a constant factor, as indicated. The right parts of the diagrams contain intensity plots of the simulated polariton spectral density for cylindrical mesas of the same diameters, yielding very good quantitative agreement of the 0D polariton states in the circular mesas. This confirms the coexistence of 0D and 2D microcavity polaritons in these semiconductor structures. This paper is an invited presentation from the 8th International Workshop on Nonlinear Optics and Excitation Kinetics. Further articles from NOEKS 8 are published in phys. stat. sol. (c) 3, No. 7 (2006). [source]

Symmetries and anisotropies of the electronic states within full spin,orbit coupling

PHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 9 2005
G. E. Marques
Abstract We have analyzed how the symmetries and the anisotropies of energy dispersions and of the spinor states, within full spin,orbit interaction, form the two independent circular spin polarizations. We also compare how the effects produced by Rashba and Dresselhauss interaction terms act on the structure of the Hilbert space. These aspects are used to envisage a voltage controlled multichannel spin-filtering regime in nonmagnetic diode structures. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Effects of lattice-mismatch induced built-in strain on the valence band properties of wurtzite ZnO/Zn1,xMgxO quantum well heterostructures

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 1 2007
K. Zitouni
Abstract We present a theoretical study of the effects of lattice-mismatch induced built-in strain on the electronic properties of valence band states in wurtzite ZnO/Zn1,xMgxO Quantum Well (QW) heterostructures. In this purpose, a 6x6 k·p method has been used to incorporate the effects of strain and nonparabolicity. The energies corresponding to the transitions between conduction band (C), heavy hole (HH), light hole (LH) and crystal-field split-off hole (CH) bands have been calculated as a function of Mg composition and strain. We have also calculated the energy dispersions and wave functions of strained wurtzite ZnO. It is found that ZnO is always under a biaxial tensile strain, in the whole Mg composition range investigated (x < 40%). As a consequence, the light hole valence subband is shifted upwards with respect to the corresponding heavy hole valence subband, resulting in a reduction of ZnO direct band gap by almost 6% when x = 35%. This is found to result in turn in a significantly reduced in-plane hole effective mass at the top of the valence band which is always LH-like. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]