Self-induced inverse spin Hall effect in ferromagnets: demonstration through non-monotonic temperature-dependence in permalloy

International audienceWe investigated the self-induced inverse spin Hall effect in ferromagnets. Temperature (T), thickness (t) and angular-dependent measurements of transverse voltage in spin pumping experiments were performed with permalloy films. Results revealed non-monotonous T-dependence of the self-induced transverse voltage. Qualitative agreement was found with first-principle calculations unravelling the skew scattering, side-jump, and intrinsic contributions to the T-dependent spin Hall conductivity. Experimental data were similar whatever the material in contact with permalloy (oxides or metals), and revealed an increase of produced current with t, demonstrating a bulk origin of the effect

1.5 μm InAs/InGaAsP/InP quantum dot laser with improved temperature stability

Temperature characteristics of InAs/InGaAsP quantum dot (QD) lasers synthesized on InP (001) substrate are presented. The lasers demonstrate high temperature stability: a threshold current characteristic temperature as high as 205 K in the temperature range between 20 to 50°C was measured. Lasing wavelength of 1.5 μm was achieved by covering QDs with 1.7 monolayers of GaAs

Cluster Approach To Model Titanium Dioxide as Isolated or Organic Dye Sensitized Nanoobjects

International audienceThis paper proposes the cluster approach methodology to simulate electronic properties of semiconducting isolated nanocrystalline materials as well as functionalized by organic dye molecules. The proposed cluster approach considers the nanoobject construction with the crystal structure in the internal part while the surface is modified according to the environmental interaction. In this aim, the (TiO2)n clusters with n = 2-140, indoline dye molecule D102, and their hybrid composites were investigated. The electronic properties of (TiO2)n were computed thanks to different DFT potentials, considering the nanobject sizes evaluation, their environmental surface modification and saturation, and the interface effects occurring between the cluster and sensitizer. The studies prove that the electronic features of (TiO2)n nanoparticles with surface being altered by the external environment may be coherently computed using DFT methodology with LC-BLYP potential by modifying the long-range separation parameter μ. The values of μ depend on the composition of the investigated system, whereas the surface saturation of the studied clusters possessing suitable size did not have any critical impact on their electronic properties. It is shown that the developed methodology is also relevant to characterize the charge transfer involved in the hybrid forms associating dye molecules and (TiO2)n clusters. The mentioned process is crucial in the efficiency of photovoltaic devices based on the hybrid systems