Cette thèse de doctorat propose d'explorer un nouveau paradigme de propagation de l'information de spin sur de très longues distances après encodage sur la polarisation de lumière cohérente. L'objectif principal de ce manuscrit est de fournir une étude détaillée de l'injection de spin dans des composants optoélectroniques III-V à géométrie verticale. Pour atteindre cet objectif, nous nous concentrons sur l'étude de l'injection optique et électrique de spin dans des structures « Light Emitting Diodes » (LEDs) et des structures « Vertical External Cavity Surface Emitting Lasers » (VECSELs) à base de semiconducteurs III-V. Nos investigations et résultats sont présentés suivant trois axes majeurs.La première partie regroupe un état de l'art sur l'injection de spin dans les composants optoélectroniques III-V et se concentre sur les phénomènes physiques engagés dans la conversion d'une accumulation de spin en information de polarisation lumineuse. Une discussion sur l'injection et le transport de spin dans des structures semi-conductrices est suivie par une analyse orientée-composant sur l'injection de spin dans les LEDs et les VCSELs.La deuxième axe s'articule autour de notre travail expérimental sur le développement et l'optimisation sur LEDs III-V d'un injecteur de spin MgO/CoFeB/Ta ultra-fin présentant une aimantation perpendiculaire à la rémanence magnétique. Nous nous focalisons en premier lieu sur l'optimisation de la barrière tunnel MgO pour maximiser l'injection de porteurs polarisés en spin et détaillons par la suite le développement et la caractérisation d’un injecteur de spin possédant une aimantation perpendiculaire à la rémanence magnétique.La troisième partie contient le travail principal de cette thèse de doctorat. Elle est entièrement consacrée à notre recherche expérimentale sur l'injection de spin dans les structures « Vertical External Cavity Surface Emitting Lasers ». Nous commençons par introduire un model vectoriel permettant la compréhension théorique de la sélection de polarisation dans les structures VECSELs injectées en spin. Nous rapportons ensuite la mesure de biréfringence d'une structure VECSEL designée pour le pompage optique en utilisant une technique expérimentale originale basée sur la mesure du décalage en fréquence entre les deux modes de polarisation orthogonaux TE et TM. Ultérieurement, nos observations et résultats sur l'injection optique de spin dans les VECSELs sont détaillés, analysés et commentés. L'étude est étendue à l'estimation des temps de vie caractéristiques du système par mesures de Photoluminescence résolues en temps afin d'évaluer l'efficacité de conversion de l'information de spin. Pour finir, les résultats préliminaires sur l'injection électrique de spin dans les VECSELs sont présentés. / This Ph.D Thesis proposes to explore a new paradigm of spin-information propagation over very long distances after encoding on coherent light polarization. The main objective of this manuscript is to provide a detailed study of spin-injection into III-V semiconductor based opto-electronic devices with vertical geometries. To achieve this goal, we focus on the study of optical and electrical spin-injection in III-V semiconductor based Light Emitting Diodes (LEDs) and Vertical External Cavity Surface Emitting Lasers (VECSELs). Our investigations and results are presented on three axes.The first part regroups a state-of-the-art of spin-injection into semiconductors optoelectronic devices and focuses on the physical phenomena engaged in the conversion of a spin accumulation into light polarization information. A discussion on spin-injection and spin-transport into III-V semiconductor structures is followed by a more device-oriented review on spin-injection in LEDs and VCSELs.The second axis is articulated around our experimental work on the development and the optimization on III-V semiconductors LEDs of an ultra-thin MgO/CoFeB/Ta spin-injector with perpendicular magnetization at magnetic remanence. We focus on the MgO tunnel barrier optimization for maximizing the spin-injection efficiency and further detailed the development and the characterization of the spin-injector with perpendicular magnetization at remanence.Finally, the third part contains the main work of this Ph.D thesis. It is fully dedicated to our experimental research on spin-injection in Vertical External Cavity Surface Emitting Laser structures. A vectorial model allowing the theoretical understanding of polarization selection in spin-injected VECSELs is first introduced. Next, we report the birefringence measurement of a VECSEL designed for optical pumping using an original frequency detuning measurement between the two orthogonal TE- and TM-modes. Afterward, our observations and results on optical spin-injection in VECSELs are displayed, analyzed and commented. The study is farther extended to the measurement of the system's characteristic lifetimes using Time Resolved Photo-Luminescence in order to evaluate the spin-information conversion efficiency. Finally the preliminary results on electrical spin-injection experiment are presented.

In the present thesis we introduce the reader to the field of spintronics and explore new phenomena, such as spin transfer torques, spin filtering, and three types of spin-orbit torques, Rashba, spin Hall, and spin swapping, which have emerged very recently and are promising candidates for a new generation of memory devices in computer technology. A general overview of these phenomena is presented in Chap. 1. In Chap. 2 we study spin transfer torques in tunnel junctions in the presence of spin filtering. In Chap. 3 we discuss the Rashba torque in ferromagnetic films, and in Chap. 4 we study spin Hall effect and spin swapping in ferromagnetic films, exploring the nature of spin-orbit torques based on these mechanisms. Conclusions and perspectives are summarized in Chap. 5.

Electrons not only have charges but also have spin. By utilizing the electron spin, the energy consumption of electronic devices can be reduced, their size can be scaled down and the efficiency of `read' and `write' in memory devices can be significantly improved. Hence, the manipulation of electron spin in electronic devices becomes more and more appealing for the advancement of microelectronics. In spin-based devices, the manipulation of ferromagnetic order parameter using electrical currents is a very useful means for current-driven operation. Nowadays, most of magnetic memory devices are based on the so-called spin transfer torque, which stems from the spin angular momentum transfer between a spin-polarized current and the magnetic order parameter. Recently, a novel spin torque effect, exploiting spin-orbit coupling in non-centrosymmetric magnets, has attracted a massive amount of attention. This thesis addresses the nature of spin-orbit coupled transport and torques in non-centrosymmetric magnetic semiconductors. We start with the theoretical study of spin orbit torque in three dimensional ferromagnetic GaMnAs. Using the Kubo formula, we calculate both the current-driven field-like torque and anti-damping-like torque. We compare the numerical results with the analytical expressions in the model case of a magnetic Rashba two-dimensional electron gas. Parametric dependencies of the different torque components and similarities to the analytical results of the Rashba two-dimensional electron gas in the weak disorder limit are described. Subsequently we study spin-orbit torques in two dimensional hexagonal crystals such as graphene, silicene, germanene and stanene. In the presence of staggered potential and exchange field, the valley degeneracy can be lifted and we obtain a valley-dependent Berry curvature, leading to a tunable antidamping torque by controlling the valley degree of freedom. This thesis then addresses the influence of the quantum spin Hall effect on spin orbit torque in nanoribbons with a hexagonal lattice. We find a dramatic modification of the nature of the torque (field like and damping-like component) when crossing the topological phase transition. The relative agnitude of the two torque components can be significantly modifies by changing the magnetization direction. Finally, motivated by recent experimental results, we conclude by investigating the features of spin-orbit torque in magnetic transition metal dichalcogenides. We find the torque is associated with the valley polarization. By changing the magnetization direction, the torque can be changed from a finite value to zero when the valley polarization decreases from a finite value to zero.

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Magnetic nanostructures provide the opportunity to investigate a number ofmagnetic phenomena, and are of interest for their possible future applicationsin technology. In this project, the ferromagnetic response (FMR) of magnetic nanostructures to an electromagnetic excitation has been investigated using the micromagnetic simulations program Mumax3. The magnetic nanostructures in question were lattices of stadium shaped magnetic islands known as square articial spin ice. They are often characterized by the vortex in which four islands meet. Depending on the number of magnetic moment directed inwards or outwards from the vortex, four main vortex types can be created according to their magnetic energy. Lattices of square articial spin ice can exhibit articial magnetic monopoles connected by Dirac strings. Four congurations of square articial spin ice were investigated: a single stadium shaped island, two single vertices of different types, a lattice of 24 magnetic islands with two different spacings and types of center vertices, and a lattice of 60 magnetic islands for the case of inserted Dirac strings. The FMR spectra of these structures reveal several resonant modes of different intensities and frequencies. Of particular interest is the relationship between the intensity of a particular resonant mode and the number of inserted stings of reversed magnetization for the 4-by-4 lattice.

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