The Influence of the Rashba spin orbit coupling on the two dimensional magnetoexcitons

Cataloged from PDF version of article.The influence of the Rashba spin-orbit coupling (RSOC) on the two-dimensional (2D) electrons and holes in a strong perpendicular magnetic field leads to different results for the Landau quantization in different spin projections. In the Landau gauge the unidimensional wave vector describing the free motion in one in-plane direction is the same for both spin projections, whereas the numbers of Landau quantization levels are different. For an electron in an s-type conduction band they differ by one, as was established earlier by Rashba (1960 Fiz. Tverd. Tela 2 1224), whereas for heavy holes in a p-type valence band influenced by the 2D symmetry of the layer they differ by three. The shifts and the rearrangements of the 2D hole Landau quantization levels on the energy scale are much larger in comparison with the case of conduction electron Landau levels. This is due to the strong influence of the magnetic field on the RSOC parameter. At sufficiently large values of this parameter the shifts and rearrangements are comparable with the hole cyclotron energy. There are two lowest spin-split Landau levels for electrons as well as four lowest ones for holes in the case of small RSOC parameters. They give rise to eight lowest energy bands of the 2D magnetoexcitons, as well as of the band-to-band quantum transitions. It is shown that three of them are dipole-active, three are quadrupole-active and two are forbidden. The optical orientation under the influence of circularly polarized light leads to optical alignment of the magnetoexcitons with different orbital momentum projections in the direction of the external magnetic field

Determination of the parameters characterizing the superexchange interaction in complex ferrite-spinels

A calculation procedure is proposed here for determining the values of exchange parameters, applicable to spinels which contain three kinds of ions in tetrahedral positions and which have an arbitrary distribution of cations. The values of exchange integrals obtained here for ferrites of the manganese-zinc system provide a useful basis for a quantitative interpretation of the spread of Curie-temperature readings in experiments which involve ferrites with the same composition. © 1976 Plenum Publishing Corporation

Study of the influence of the design of the turning tool on the removal of thermal energy from the cutting zone

In this work, we performed a study and developed the design of through-cutters that provide accelerated heat removal from the cutting zone with external turning. Using SolidWorks Simulation engineering analysis and SolidWorks Flow Simulation gas-hydrodynamic analysis modules as a research tool, we created a basic 3D model of a precast cutter and carried out a thermal analysis of the transition process to determine the distribution of temperature fields in the body of the cutter throughout time during the cutting process. After that, we made changes to the design of the cutter, specifically, created a cavity in the holder body in which the copper core was placed. We then re-performed the studies described above, which showed that when using a copper core, the temperature in the cutting zone decreases by 246 C within 15 minutes from the start of the work. To obtain a greater effect, we added a hole in the copper core and used air cooling, which allowed reducing the temperature in the cutting zone by 313 C. © Published under licence by IOP Publishing Ltd