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Electronic states and spectra of NpO(2)(2+) and NpO(2)Cl(4)(2-) with a Np 5f(1) ground-state configuration, related to low-lying 5f-5f and ligand-to-metal charge-transfer (CT) transitions, are investigated, using restricted-active-space perturbation theory (RASPT2) with spin-orbit coupling. Restrictions on the antibonding orbital occupations have little influence on the 5f-5f transition energies, but an important impact on the CT states with an open bonding orbital shell. The present calculations provide significant improvement over previous literature results. The assignment of the experimental electronic spectra of Cs(2)NpO(2)Cl(4) is refined, based on our calculations of NpO(2)Cl(4)(2-). Assignments on the basis of bare NpO(2)(2+) are less reliable, since the equatorial Cl ligands perturb the excited-state energies considerably. Calculated changes of the Np-O bond lengths are in agreement with the observed short symmetric-stretching progressions in the f-f spectra and longer progressions in the CT spectra of neptunyl. A possible luminescence spectrum of the lowest quartet CT state is predicted.

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We investigate theoretically the spin states in InAs/AlSb/GaSb broken-gap quantum wells by solving the Kane model and the Poisson equation self-consistently. The spin states in InAs/AlSb/GaSb quantum wells are quite different from those obtained by the single-band Rashba model due to the electron-hole hybridization. The Rashba spin-splitting of the lowest conduction subband shows an oscillating behavior. The D'yakonov-Perel' spin relaxation time shows several peaks with increasing the Fermi wavevector. By inserting an AlSb barrier between the InAs and GaSb layers, the hybridization can be greatly reduced. Consequently, the spin orientation, the spin splitting, and the D'yakonov-Perel' spin relaxation time can be tuned significantly by changing the thickness of the AlSb barrier.

We demonstrate theoretically that electric field can drive a quantum phase transition between band insulator to topological insulator in CdTe/HgCdTe/CdTe quantum wells. The numerical results suggest that the electric field could be used as a switch to turn on or off the topological insulator phase, and temperature can affect significantly the phase diagram for different gate voltage and compositions. Our theoretical results provide us an efficient way to manipulate the quantum phase of HgTe quantum wells. PACS numbers: 73.43.Nq, 72.25.Rb, 73.61.Ga, Topological insulator (TI) is a very recent discovery and has attracted a rapid growing interests due to its novel transport peoperty 1,2,3,4 . Topological insulators possess a gap in the bulk but a gapless edge states at its boundary, therefore display remarkable transport property due to the presence of the topological edge states, e.g., quantum spin Hall effect (QSHE). The QSHE is protected by the time-reversal symmetry and robust against the local perturbation, e.g., impurity scattering. Searching for new TI becomes a central issue in this rapid growing field. Recently, the HgTe QWs have been demonstrated to be a 2D TI to exhibit the QSHE 3 and BiSb alloys have been proven to be a 3D TI with a conducting surface 5 . A few other materials, such as InAs/GaSb QWs, BiSe, BiTe and SbTe alloys 6 , are also predicted to be TIs and demonstrated experimentally. Besides finding new TI materials, searching the ways to drive a band insulator (BI) into a topological insulator is also important. It has been demonstrated to be possibly realized by tuning the thickness of HgTe QW. However, tuning the thickness of QW is not a convenient way to drive the phase transition. Therefore other efficient ways such as external fields and temperature is highly desirable to drive a BI into a TI. These ways would be very important for both potential device applications and basic physics.In this Letter, we demonstrate theoretically that a BI can be driven into a TI by tuning external electric field in CdTe/Hg 1−x Cd x Te/CdTe QWs based on the self-consistent calculation of the eight-band Kane model and the Poisson equation. We demonstrate electric field can change the interband coupling significantly and consequently leads to strong variations of the band structures, i.e., therefore leads to the quantum phase transition from a BI to a TI. We also show phase diagrams at plenty of parameters and consider the temperature effect on the phase transition. One can see that the critical gate voltage of external phase transition can be reduced at high temperature, small Cd composition and thick thickness of well. Our results could be useful in finding the optimized parameters to realize the phase transition in experiment.We consider a CdTe/Hg 1−x Cd x Te/CdTe QW grown along the [001] direction [see Fig. 1 (a) inside the QW will redistribute due to the effect of the electric field. The charge redistribution induces an internal electric field, which affects the charge density distribution, therefore we n...

We extend profound results in pluripotential theory on Kähler manifolds [31] to Sasaki setting via its transverse Kähler structure. As in Kähler case, these results form a very important piece to solve the existence of Sasaki metrics with constant scalar curvature (cscs) in terms of properness of K-energy, considered by the first named author in [49]. One main result is to generalize T. Darvas' theory on the geometric structure of the space of Kähler potentials in Sasaki setting. Along the way we extend most of corresponding results in pluripotential theory to Sasaki setting via its transverse Kähler structure.

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Kinetic and relativistic effects on the surface alloy formation of submonolayer Au adsorbed on Si(111)-×-Pb surface Appl. Phys. Lett. 99, 211912 (2011) Spin-polarized transport in zigzag graphene nanoribbons with Rashba spin-orbit interaction J. Appl. Phys. 110, 103702 (2011) Excitonic couplings and Stark effect in individual quantum dot molecules J. Appl. Phys. 110, 083511 (2011) Rashba diamond in an Aharonov-Casher ring Appl. Phys. Lett. 99, 142507 (2011) Giant in-plane anisotropy in manganite thin films driven by strain-engineered double exchange interaction and electronic phase separation Appl. Phys. Lett. 99, 122510 (2011) Additional information on Appl. Phys. Lett. We theoretically investigate the Rashba spin-orbit interaction in InAs/ GaSb quantum wells ͑QWs͒. We find that the Rashba spin-splitting ͑RSS͒ sensitively depends on the thickness of the InAs layer. The RSS exhibits nonlinear behavior for narrow InAs/ GaSb QWs and the oscillating feature for wide InAs/ GaSb QWs. The nonlinear and oscillating behaviors arise from the weakened and enhanced interband coupling. The RSS also show asymmetric features respect to the direction of the external electric field.