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In our previous paper [T. Fordos, et al., J. Opt. 16 (2014) 065008] we have proposed a new approach for modeling of polarized light emission from anisotropic multilayers with active dipole layers. The method is suitable to model spin-polarized light emitting diodes (spin-LED) and spin-lasers. This paper deals with generalization of the approach to scattering matrix (S-matrix) formalism and to laterally periodic structures in the frame of rigorous coupled wave algorithm (RCWA). We use expansion of the permittivity tensor in a grating layer into Fourier series and the periodic electromagnetic field in the structure is expressed using a matrix method including appropriate boundary conditions. The new approach based on S-matrix formalism is also suitable for modeling of monomode emission from MQW laser structures with multiple source layers.

The anisotropic properties of thermal transport in insulating or conducting ferromagnets are derived on the basis of the Onsager reciprocity relations applied to a magnetic system. It is shown that the angular dependence of the temperature gradient takes the same form as that of the anisotropic magnetoresistance, including anomalous and planar Hall contributions [1]. The experimental study [2] shows that the voltage measured between the extremities of the non-magnetic electrode in thermal contact to the Py or YIG ferromagnetic layers follows the predicted angular dependence. Furthermore, the sign and the amplitude of the magneto-voltaic signal measured is in agreement with the thermocouples calculated from the corresponding Seebeck coefficients, for the three different electrodes used in the study (Pt, Cu, Bi).

This work reports on investigations into the possibility of harvesting energy from the piezoelectric response of millimetric ZnO rods to movement. SEM & PL studies of hydrothermally grown ZnO rods revealed sizes ranging from 1 - 3 mm x 100 - 400 microns and suggested that each was a wurtzite monocrystal. Studies of current & voltage responses as a function of time during bending with a probe arm gave responses coherent with those reported elsewhere in the literature for ZnO nanowires or micro-rod single wire generators. The larger scale of these rods provided some advantages over such nano- and microstructures in terms of contacting ease, signal level & robustness.

GaN was grown on ZnO-buffered c-sapphire (c-Al2O3) substrates by Metal Organic Vapor Phase Epitaxy. The ZnO then served as a sacrificial release layer, allowing chemical lift-off of the GaN from the c-Al2O3 substrate via selective wet etching of the ZnO. The GaN was subsequently direct-wafer-bonded onto a glass substrate. X-Ray Diffraction, Scanning Electron Microscopy, Energy Dispersive X-ray microanalysis, Room Temperature Photoluminescence & optical microscopy confirmed bonding of several mm2 of crack-free wurtzite GaN films onto a soda lime glass microscope slide with no obvious deterioration of the GaN morphology. Using such an approach, InGaN based devices can be lifted-off expensive single crystal substrates and bonded onto supports with a better cost-performance profile. Moreover, the approach offers the possibility of reclaiming and reusing the substrate.

Recently, there has been a surge of activity in the development of next-generation transparent thin film transistors for use in applications such as electronic paper and flexible organic light emitting diode panels. Amongst the transparent conducting oxides attracting the most interest at present are Amorphous Oxide Semiconductors (AOS) based on ZnO because they exhibit enhanced electron mobility (μ), superior capacity for processability in air and improved thermodynamic stability compared with conventional covalent amorphous semiconductors and existing AOS. Moreover, they give excellent performance when fabricated at relatively low temperature and can readily be made in large area format. Thus, they are projected to resolve the trade-off between processing temperature and device performance and thereby allow fabrication on inexpensive heatsensitive substrates. For the moment, however, an undesireable post-deposition annealing step at a temperature of about 200°C is necessary in order to obtain suitable electrical and optical properties. This paper demonstrates the possibility of directly engineering amorphous ZnO with relatively high conductiviy at room temperature on paper and mylar substrates using pulsed laser deposition.

We present the last developments of the approach of spin-transfer in terms of mesoscopic non-equilibrium thermodynamics. The modification of the ferromagnetic states due to the presence of a spin-accumulation process is investigated. The spin accumulation (also responsible for giant magnetoresistance) is generated by an electric current at the interfaces with a ferromagnetic nanostructure. The dynamical coupling that links the ferromagnetic degree of freedom to the spin of the conduction electrons is investigated with taking into account longitudinal and transverse spin accumulation. It seems that the coupling with the transverse spin-accumulation may be equivalent to the usual spin-transfer-torque mechanisms deduced from microscopic transmission- reflection coefficients at the interface. In contrast, the coupling with the longitudinal spin- accumulation generates fluctuations and seems to play important role in the activation process at larger time scales only.

The aim of this paper is to demonstrate the relevance of the a non-equilibrium stochastic approach in the context of spin-transfer mechanism. Spin-transfer is the generic name for the effect of magnetization reversal (or magnetic excitation) produced by the injection of a spin-polarized current in a ferromagnetic layer. Deterministic vs. stochastic approaches are first defined in the context of the Landau-Lifshitz Gilbert equation of the magnetization. We then present a model based on non-equilibrium thermodynamics in which the spin-accumulation at the interface appears as a diffusion term in the Landau-Lifshitz equation. The expression of the critical current I c is derived from this diffusive process and compared to the experimental results. Due to the definition of the critical current in terms of activation process, the phenomenological expression of I c is identical to that derived in the deterministic case, after introducing an "efficiency parameter". Only the specific form of this efficiency parameter allows one to discriminate between the different models. The direct link to the integral of the magnetoresistance of the junction derived here allows some highly specific behaviour to be predicted.

Spin injection in metallic normal/ferromagnetic junctions is investigated taking into account the anisotropic magnetoresistance occurring in the ferromagnetic layer. On the basis of a generalized two-channel model, it is shown that there is an interface resistance contribution due to anisotropic scattering, besides spin accumulation and giant magnetoresistance. The corresponding expression of the thermoelectric power is derived and compared with the expression accounting for the thermoelectric power produced by the giant magnetoresistance. The results of this study show that, while the giant magnetoresistance and the corresponding thermoelectric power indicate the role of spin-flip scattering, the observed anisotropic magneto-thermoelectric power might be the fingerprint of interband s-d relaxation mechanisms.