Nanoscale spin-polarization in dilute magnetic semiconductor (In,Mn)Sb

Results of point contact Andreev reflection (PCAR) experiments on (In,Mn)Sb are presented and analyzed in terms of current models of charge conversion at a superconductor-ferromagnet interface. We investigate the influence of surface transparency, and study the crossover from ballistic to diffusive transport regime as contact size is varied. Application of a Nb tip to a (In,Mn)Sb sample with Curie temperature Tc of 5.4 K allowed the determination of spin-polarization when the ferromagnetic phase transition temperature is crossed. We find a striking difference between the temperature dependence of the local spin polarization and of the macroscopic magnetization, and demonstrate that nanoscale clusters with magnetization close to the saturated value are present even well above the magnetic phase transition temperature.Comment: 4 page

A Review of the Adults and Larvae of the Genus \u3ci\u3ePycnopsyche\u3c/i\u3e (Trichoptera: Limnephilidae) with Revision of the \u3ci\u3ePycnopsyche scabripennis\u3c/i\u3e (Rambur) and \u3ci\u3ePycnopsyche lepida\u3c/i\u3e (Hagen) Complexes

The adults and larvae of the genus Pycnopsyche are reviewed. Nineteen species are recognized for the genus. The males and females of all species are described and illustrated. All species accounts include description, diagnosis, type locality, distribution, variation, notes and material examined sections. The P. scabripennis complex is revised, and three distinct species are recognized (P. scabripennis s.s., P. antica, and P. conspersa). The P. lepida group (P. lepida, P. indiana, P. subfasciata, and P. virginica) is also revised with all species remaining recognized; however, P. virginica is removed from the complex. Two new species are described for the genus but will be named in a separate publication (herein identified as P. sp. A and P. sp. B). Keys are provided for all adults of both sexes. The larvae of sixteen species are described and/or discussed. A number of these were reared for the first time. Because of the conservativeness of larval morphology as a whole, many of the larvae can not be successfully identified below the level of groups of species. Keys to larvae are not included because of this difficulty. Known distributions of the species in the genus are updated utilizing information from published and unpublished sources. Maps plotted by county (U. S. records) or site (Canada records) are included. Finally, a preliminary discussion of phylogenetic relationships in the genus is provided. Based on this discussion the genus is modified from the five species groups of Schmid (1955) to a total of eight groups

Spin diffusion in the Mn2+ ion system of II-VI diluted magnetic semiconductor heterostructures

The magnetization dynamics in diluted magnetic semiconductor heterostructures based on (Zn,Mn)Se and (Cd,Mn)Te has been studied experimentally by optical methods and simulated numerically. In the samples with nonhomogeneous magnetic ion distribution this dynamics is contributed by spin-lattice relaxation and spin diffusion in the Mn spin system. The spin diffusion coefficient of 7x10^(-8) cm^2/s has been evaluated for Zn(0.99)Mn(0.01)Se from comparison of experimental and numerical results. Calculations of the giant Zeeman splitting of the exciton states and the magnetization dynamics in the ordered alloys and parabolic quantum wells fabricated by the digital growth technique show perfect agreement with the experimental data. In both structure types the spin diffusion has an essential contribution to the magnetization dynamics.Comment: 12 pages, 11 figure

Coulomb-driven organization and enhancement of spin-orbit fields in collective spin excitations

Spin-orbit (SO) fields in a spin-polarized electron gas are studied by angle-resolved inelastic light scattering on a CdMnTe quantum well. We demonstrate a striking organization and enhancement of SO fields acting on the collective spin excitation (spin-flip wave). While individual electronic SO fields have a broadly distributed momentum dependence, giving rise to D'yakonov-Perel' dephasing, the collective spin dynamics is governed by a single collective SO field which is drastically enhanced due to many-body effects. The enhancement factor is experimentally determined. These results provide a powerful indication that these constructive phenomena are universal to collective spin excitations of conducting systems.Comment: 5 pages, 4 figure

Definitive observation of the dark triplet ground state of charged excitons in high magnetic fields

The ground state of negatively charged excitons (trions) in high magnetic fields is shown to be a dark triplet state, confirming long-standing theoretical predictions. Photoluminescence (PL), reflection, and PL excitation spectroscopy of CdTe quantum wells reveal that the dark triplet trion has lower energy than the singlet trion above 24 Tesla. The singlet-triplet crossover is "hidden" (i.e., the spectral lines themselves do not cross due to different Zeeman energies), but is confirmed by temperature-dependent PL above and below 24 T. The data also show two bright triplet states.Comment: 4 figure

Incidence of bone formation by whole bone marrow cell suspensions and by its stromal cell cultures injected into kidney parenchyma of Balb/c mice

The evaluation of incidence of bone formation by whole syngeneic bone marrow cell suspension and by bone marrow stromal cell cultured in vitro injection into kidney parenchyma was done. Bone tissue was found in 26 kidneys out of 100 injected with whole bone marrow cells suspension. Cultured stromal bone marrow cells grafted into kidney parenchyma produced ossicles in only 4 out of 101 injected kidneys. Such low incidence of bone forming ability of the marrow stromal cell cultures grafted into kidney indicate their useless for study on bone histogenesis in the kidney by murine marrow stromal cell cultures

Fractional quantum Hall effect in CdTe

The fractional quantum Hall (FQH) effect is reported in a high mobility CdTe quantum well at mK temperatures. Fully-developed FQH states are observed at filling factor 4/3 and 5/3 and are found to be both spin-polarized ground state for which the lowest energy excitation is not a spin-flip. This can be accounted for by the relatively high intrinsic Zeeman energy in this single valley 2D electron gas. FQH minima are also observed in the first excited (N=1) Landau level at filling factor 7/3 and 8/3 for intermediate temperatures.Comment: Submitte