Spin-dependent proximity effects in ferromagnetic semiconductor/superconductor structures

Proximity effects in normal metal/insulator/ferromagnetic semiconductor/superconductor (NM/I/FS/SC) and NM/I/SC/FS junctions are studied based on an extended Blonder-Tinkham-Klapwijk (BTK) theory. It is found that the magnitude of the proximity effects depends to a great extent on the mismatches of the effective mass and band between the FS and SC. For NM/I/FS/SC junction, the transition of the tunneling conductance from “0” to “π” state is determined by the mass, magnetic exchange energy in FS and the thickness of FS. For NM/I/SC/FS junctions, the conductance spectrum is spin-dependent, indicating a local coexistence of weak ferromagnetism and s-wave superconductivity.     

First-principles study on the structural and electronic properties of ultrathin ZnO nanofilms

Using first-principles density-functional calculations, we have studied the structural and electronic properties of ultrathin ZnO {0001} nanofilms. The structural parameters, the charge densities, band structures and density of states have been investigated. The results show that there are remarkable charge transfers from Zn to O atoms in the ZnO nanofilms. All the ZnO nanofilms exhibit direct wide band gaps compared with bulk counterpart, and the gap decreases with increased thickness of the nanofilms. The decreased band gap is associated with the weaker ionic bonding within layers and the less localization of electrons in thicker films. A staircase-like density of states occurs at the bottom of conduction band, indicating the two-dimensional quantum effects in ZnO nanofilms.     

Relativistic effects on complexity indexes in atoms in position and momentum spaces

Three different statistical measures of complexity are explored for the atoms He to Ra. The measures are analysed in both position and momentum spaces. Relativistic effects on the complexity indexes are systematically studied. These effects are discussed in terms of the information content factor and the disorder terms of the complexity indexes. Relativistic and non-relativistic complexity indexes are calculated from Optimized Effective Potential densities.     

The aqueous Raman optical activity spectra of 4(R)‐hydroxyproline: theory and experiment

Vibrational Raman optical activity (ROA) spectra have been measured for aqueous solutions of 4(R)‐hydroxyproline at three different pH values and are compared with theoretical results calculated for several conformations of anionic, cationic and zwitterionic 4(R)‐hydroxyproline using density functional theory (DFT) and the polarizable continuum model (PCM). The experimental ROA bands have been ascribed to the normal modes by comparison of the experimental and calculated vibrational frequencies and ROA intensities. Overall, using PCM for geometry optimization and force field calculations gives simulated Raman and ROA spectra that agree with the main features of the experimental spectra, whereas using PCM also in the calculations of optical tensors seems more problematic. Copyright © 2010 John Wiley & Sons, Ltd.