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This paper presents application of line surge arresters on the compact transmission lines. Single and double circuit compact transmission lines are considered. Line lightning performance is computed using sigma slp simulation software. Different line surge arrester installation configurations are considered. Line lightning performance is computed for different tower footing resistance. Line performance before and after line surge arrester installation are compared. Line lightning performance of the unshielded line with line surge arresters is compared with the performance of the shielded line without line surge arresters. For double circuit shielded compact lines, double circuit outage rate is computed. Influence of the tower footing resistance on the double circuit outage rate is presented.

THz spintronics emitters represent today novel sources for broadband emission using nanometer-scaled materials. We experimentally investigate and model THz spintronic emission based on the spin Hall effect in 3d/5d transition metals and on the inverse Rashba-Edelstein effect in the optimized topological insulator Bi1-xSbx.

We present experimental and numerical results on the magnetization reversal induced by spin–orbit torques of micronic disks of a ferromagnetic multilayer with perpendicular magnetic anisotropy on top of a Pt track: Pt (6 nm)/[Co(0.2 nm)/Ni(0.6 nm)] × 5/Al(5 nm). The current induced magnetization switching process is probed by anomalous Hall effect measurements and Kerr microscopy. The electrical characterization reveals the critical current for the complete reversal to be about 3×1011 A/m2, and Kerr microscopy uncovers a deterministic nucleation that depends on current and field polarity. Through the use of experimental switching phase diagrams coupled to micromagnetic simulations, we evaluated the field-like to damping-like torque ratio to be 0.73 ± 0.05, which is in good agreement with experimental values observed by second harmonic measurements. These measurements emphasize an unexpectedly large field-like contribution in this relatively thick Co/Ni multilayer (4 nm). In light of these experiments and simulations, we discuss the key parameters needed to understand the magnetization reversal, namely, the field and damping-like torques and the Dzyaloshinskii–Moriya interaction.

International audience; Perpendicularly magnetized spin injector with high Curie temperature is a prerequisite for developing spin optoelectronic devices on 2D materials working at room temperature (RT) with zero applied magnetic field. Here, we report the growth of Ta/CoFeB/MgO structures with a large perpendicular magnetic anisotropy (PMA) on full coverage monolayer (ML) MoS2. A large perpendicular interface anisotropy energy of 0.975mJ/m 2 has been obtained at the CoFeB/MgO interface, comparable to that observed in magnetic tunnel junction systems. It is found that the insertion of MgO between the ferromagnetic metal (FM) and the 2D material can effectively prevent the diffusion of the FM atoms into the 2D material. Moreover, the MoS2 ML favors a MgO(001) texture and plays a critical role to establish the large PMA. First principle calculations on a similar Fe/MgO/MoS2 structure reveal that the MgO thickness can modify the MoS2 band structure, from an indirect bandgap with 7ML-MgO to a direct bandgap with 3ML-MgO. Proximity effect induced by Fe results in a splitting of 10meV in the valence band at the Γ point for the 3ML-MgO structure while it is negligible for the 7ML-MgO structure. These results pave the way to develop RT spin optoelectronic devices on 2D transition-metal dichalcogenide materials.

The dynamics of micrometer-sized magnetic domains in ultra-thin ferromagnetic films is so dramatically slowed down by quenched disorder that the spontaneous elastic tension collapse becomes unobservable at ambient temperature. By magneto-optical imaging we show that a weak zero-bias AC magnetic field can assist such curvature-driven collapse, making the area of a bubble to reduce at a measurable rate, in spite of the negligible effect that the same curvature has on the average creep motion driven by a comparable DC field. An analytical model explains this phenomenon quantitatively., 5 pages, 3 figures. Ancillary Material included

In this article, the effects of ultraviolet light (UV) and moisture exposure on the low-velocity impact behavior of three different carbon fiber (CF) laminate composites (unidirectional fibers, plain weave woven fibers, and non-crimp fibers (NCF)) are reported based on the experimental observations. The composite laminate was fabricated by vacuum bagging method following the manufacturing specifications with symmetric and asymmetric stacking, and then the test coupons were extracted for impact testing, C-scan, and surface characterization studies before and after UV light and moisture exposures. A low-velocity impact test was carried out to evaluate the damage resistance and tolerance of the laminate specimens. The test outcomes uncovered that the NCF laminates were far predominant in load-carrying capacity than the woven and unidirectional laminates, with the NCF-asymmetric (NCF-NS) laminate exhibiting the greater load-carrying capacity of 3017.7 kN/m and impact energy of 7.07 kJ/m (NCF-NS). The NCF-symmetric (NCF-S) laminate showing impact energy of 7.0 kJ/m and load-carrying capacity of 2886.8 kN/m with some decrease after UV and moisture exposure for both cases. The ultrasonic C-scan revealed that NCF laminates, both NCF-S and NCF-NS, have the least penetration indicating greater out of plane fracture toughness and damage tolerance. The NCF-NS laminate has the least damage area (33.35 mm2) and dent depth (0.12 mm) as compared with other laminate studied here. The wettability of the panels was similar; however, the woven (baseline) panel showed the highest water contact angle (112°). After the UV and salt fog exposure, the contact angles of the composite panels were reduced between 66° and 58°. In addition, this study also reveals the effect of stacking sequence on the impact properties of the NCF composite laminate.

Topological insulators are good candidates for charge to spin conversion with high efficiency due to their spin-polarized topological surface states (TSSs). In this work, we provide experimental evidence for two-dimensional (2D) TSSs in ${(\mathrm{Sn}{\mathrm{Bi}}_{2}{\mathrm{Te}}_{4})}_{n} {({\mathrm{Bi}}_{2}{\mathrm{Te}}_{3})}_{m}$ natural van der Waals superlattices grown by molecular beam epitaxy using angle resolved photoelectron spectroscopy and magnetotransport. While the TSSs overlap with bulk conduction band (BCB) states at the Fermi energy, it is shown that by increasing the Sn composition, the influence of BCB states is reduced and becomes minimum for $\mathrm{Sn}{\mathrm{Bi}}_{2}{\mathrm{Te}}_{4}$. The latter compound, found to be in the form of septuplet layers, shows weak antilocalization effect with a prefactor $\ensuremath{\alpha}\ensuremath{\sim}--0.41$, indicating that the TSSs and the bulk behave as one 2D channel in which magnetotransport properties are influenced by large spin-orbit coupling.

THz spintronics emitters represent today novel sources for broadband emission using nanometer-scaled materials. We present and model the THz spintronic emission based on the spin Hall effect in 3d metals and on the inverse Rashba-Edelstein effect in the optimized topological insulator Bi1 -x Sbx.

Spintronic structures are extensively investigated for their spin orbit torque properties, required for magnetic commutation functionalities. Current progress in these materials is dependent on the interface engineering for the optimization of spin transmission. Here, we advance the analysis of ultrafast spin-charge conversion phenomena at ferromagnetic-transition metal interfaces due to their inverse spin-Hall effect properties. In particular the intrinsic inverse spin Hall effect of Pt-based systems and extrinsic inverse spin-Hall effect of Au:W and Au:Ta in NiFe/Au:(W,Ta) bilayers are investigated. The spin-charge conversion is probed by complementary techniques -- ultrafast THz time domain spectroscopy in the dynamic regime for THz pulse emission and ferromagnetic resonance spin-pumping measurements in the GHz regime in the steady state -- to determine the role played by the material properties, resistivities, spin transmission at metallic interfaces and spin-flip rates. These measurements show the correspondence between the THz time domain spectroscopy and ferromagnetic spin-pumping for the different set of samples in term of the spin mixing conductance. The latter quantity is a critical parameter, determining the strength of the THz emission from spintronic interfaces. This is further supported by ab-initio calculations, simulations and analysis of the spin-diffusion and spin relaxation of carriers within the multilayers in the time domain, permitting to determine the main trends and the role of spin transmission at interfaces. This work illustrates that time domain spectroscopy for spin-based THz emission is a powerful technique to probe spin-dynamics at active spintronic interfaces and to extract key material properties for spin-charge conversion., Comment: 20 pages

Terahertz (THz) emission spectroscopy in spin systems has become a very powerful method to generate THz radiation and to investigate the properties of Rashba or Topological Insulator surface states. Broadband THz emission can be generated in heavy metallic or in more general Rashba systems. In 3d/5d transient metal bilayers THz emission is via the Inverse Spin Hall effect. Beyond heavy metal structures, Rashba states are strong candidates for THz-spintronics owing to their high spin to charge conversion properties. Here we present a 2D Electron Gas with strong Rashba spin-orbit coupling, NiFe/LaAlO 3 /SrTiO 3 , and demonstrate THz emission is via the Inverse Edelstein Effect.

Per the renewed interest in the magnetic properties of ultrathin multilayers for spintronics, the authors show how electrical-transport characterization can provide crucial information about reversal mechanisms between different magnetic configurations in synthetic antiferromagnetic (SAF) multilayers, with or without perpendicular anisotropy. Here competition between different magnetoresistive effects provides information about the system's magnetic properties and the proportions of all magnetization components in the stabilized magnetic textures. This work extends previous possibilities toward the detection of isolated magnetic domains, spin spirals, or even skyrmions in SAF systems.

Comment: to appear in Advanced Optical materials (02/2022), Spin-to-charge conversion (SCC) involving topological surface states (TSS) is one of the most promising routes for highly efficient spintronic devices for terahertz (THz) emission. Here, the THz generation generally occurs mainly via SCC consisting in efficient dynamical spin injection into spin-locked TSS. In this work, we demonstrate sizable THz emission from a nanometric thick topological insultator (TI)/ferromagnetic junction - SnBi$_2$Te$_4$/Co - specifically designed to avoid bulk band crossing with the TSS at the Fermi level, unlike its parent material Bi$_2$Te$_3$. THz emission time domain spectroscopy (TDS) is used to indicate the TSS contribution to the SCC by investigating the TI thickness and angular dependence of the THz emission. This work illustrates THz emission TDS as a powerful tool alongside angular resolved photoemission spectroscopy (ARPES) methods to investigate the interfacial spintronic properties of TI/ferromagnet bilayers.

The structure inversion asymmetry at surfaces and interfaces give rise to the Rashba spin-orbit interaction (SOI), that breaks the spin degeneracy of surface or interface states. Hence, when an electric current runs through a surface or interface, this Rashba effect generates an effective magnetic field acting on the electron spin. This provides an additional tool to manipulate the spin state in materials such as Si and Ge that, in their bulk form, possess inversion symmetry (or lack structural inersion asymmetry). The existence of Rashba states could be demonstrated by photoemission spectroscopy at the interface between different metals and Ge(111) and by spin-charge conversion experiments at the Fe/Ge(111) interface even though made of two light elements. In this work, we identify the fingerprint of the Rashba states at the Fe/Ge(111) interface by magnetotransport measurements in the form of a large unidirectional magnetoresistance of up to 0.1 \%. From its temperature dependence, we find that the Rashba energy splitting is larger than in pure Ge(111) subsurface states., 6 pages, 5 figures

People with chronic pain faced potential treatment disruption during the COVID-19 pandemic in Singapore, as the focus of healthcare shifted. A model of rapid integration of a pain centre with community healthcare teams was implemented to care for vulnerable older patients with chronic pain and multiple comorbidities. Telemedicine and home visits by community nurses were used, with risk-mitigation measures, ensuring comprehensive assessment and treatment compliance. Medications from pain physicians were delivered at home through a hospital pharmacy. A secure national electronic health records system used by all teams ensured seamless access and documentation. Potential emergency department visits, admissions and delayed discharges were thus avoided. Integration of community teams with chronic pain management services can be recommended to ensure pandemic preparedness.

We have evidenced unconventional anomalous Hall effects (AHEs) in $3d/5d$ (${\mathrm{Co}0.2\mathrm{nm}/\mathrm{Ni}0.6\mathrm{nm})}_{N}$ multilayers grown on a thin Pt layer or thin Au:W alloys with perpendicular magnetic anisotropy (PMA) properties. The inversion of AHEs observed with one Pt series is explained by considering the opposite sign of the effective spin-orbit coupling of Pt compared to Co/Ni combined with peculiar specular electronic reflections. Using advanced simulations methods for the description of the spin-current profiles based on the spin-dependent Boltzmann formalism, we extracted the spin-Hall angle (SHA) of Pt and Co/Ni of opposite sign. The extracted SHA for Pt, $+20%$, is opposite to the one of Co/Ni, giving rise to an effective AHE inversion for thin Co/Ni multilayers (with the number of repetition layers $Nl17$). The spin-Hall angle in Pt is found to be larger than the one previously measured by complementary spin-pumping inverse spin-Hall effect experiments in a geometry of current perpendicular to the plane. Whereas magnetic proximity effects cannot explain the effect, spin-current leakage and spin-orbit assisted electron scattering at Pt/(Co,Ni) interfaces fit the experiments. We also extract the main relevant electronic transport parameters governing the overall effects in current-in-plane (CIP) currents and demonstrate, in particular, that the specularity/nonspecularity in the electronic diffusion processes play an essential role to explain the observed results.

We report on efficient spin injection in p-doped $(\mathrm{In},\mathrm{Ga})\mathrm{As}/\mathrm{Ga}\mathrm{As}$ quantum-dot (QD) spin light-emitting diodes (spin LEDs) under zero applied magnetic field. A high degree of electroluminescence circular polarization (${P}_{c}$) \ensuremath{\sim}19% is measured in remanence up to 100 K. This result is obtained thanks to the combination of a perpendicularly magnetized $\mathrm{Co}\text{\ensuremath{-}}\mathrm{Fe}\text{\ensuremath{-}}\mathrm{B}/\mathrm{Mg}\mathrm{O}$ spin injector allowing efficient spin injection and an appropriate p-doped $(\mathrm{In},\mathrm{Ga})\mathrm{As}/\mathrm{Ga}\mathrm{As}$ QD layer in the active region. By analyzing the bias and temperature dependence of the electroluminescence circular polarization, we evidence a two-step spin-relaxation process. The first step occurs when electrons tunnel through the $\mathrm{Mg}\mathrm{O}$ barrier and travel across the $\mathrm{Ga}\mathrm{As}$ depletion layer. The spin relaxation is dominated by the Dyakonov-Perel mechanism related to the kinetic energy of electrons, which is characterized by a bias-dependent ${P}_{c}$. The second step occurs when electrons are captured into QDs prior to their radiative recombination with holes. The temperature dependence of ${P}_{c}$ reflects the temperature-induced modification of the QD doping, together with the variation of the ratio between the charge-carrier lifetime and the spin-relaxation time inside the QDs. The understanding of these spin-relaxation mechanisms is essential to improve the performance of spin LEDs for future spin optoelectronic applications at room temperature under zero applied magnetic field.

International audience; Photon helicity-dependent photocurrent is measured at zero magnefic field thanks to a device based on an ensemble of (In,Ga)As/GaAs quantum dots that are embedded into a GaAs-based p-in diode. Our main goal is to take advantage of the long electron spin-relaxation time expected in these nano-objects. In these experiments, no external magnetic field is required thanks to the use of an ultrathin magnetic CoFeB/MgO electrode, presenting perpendicular magnetic anisotropy. We observe a clear asymmetry of the photocurrent measured under respective right and left polarized light that follows the hysteresis of the magnetic layer. The amplitude of this asymmetry at zero magnetic field decreases with increasing temperatures and can be controlled with the bias. Polarization-resolved photoluminescence is detected in parallel while the device is operated as a photodetector. This demonstrates the multifunctional capabilities of the device and gives valuable insights into the spin relaxation of the electrons in the quantum dots.

The requirements for UHVDC installations in terms of length, mechanical strength, permissible deflection, creepage distance, shed profiles and pollution resistance are still a challenge for all existing technologies and solutions. Based on the positive long time experience with solid core porcelain post insulators and the pollution experience of insulators with silicone housings the fundamental concept of both were used to develop a new type post insulator with inside ceramic core and housing of silicone. The challenge was to provide a reliable and economical solution, which combines the advantages of both technologies. Realising the needs for high strength, low deflection under load for many applications PPC Insulators Austria began the development of hybrid post insulators. The ceramic solid core design provides superior advantages in terms of bending strength, also for torsion load and compression load. The silicone rubber housing allows thinner sheds and greater creepage distances, provides improved long term pollution flashover performance and protects the core from short circuit arc damage. As design for DC hybrid post insulators was chosen upright tapered, uniform and underhung tapered insulators columns stacked of single hybrid insulator sections. The single sections could be varied in core diameter, length, creepage distance, fittings and holepattern. The shed profile used for DC applications was defined according the recommendations given by CIGRE. Selected design tests, electrical and mechanical type tests were conducted according to the relevant parts of IEC standards for composite and ceramic insulators. Also a long term test installation was performed to establish a confidence in this product. The long term test installation has been energized at 725 kV DC and later the voltage was increased to 761 kV DC. The tests have served well in providing final qualification. Beside these voltage tests measurements of ESDD/NSDD, hydrophobicity and also visual inspections were carried out. The mechanical properties were driven from the seismic requirements and have been calculated by finite element modelling of the reactor and its support structure. For post insulators with silicone rubber sheds and with solid core porcelain may be the most stable solution and this type has been adopted in different 800 kV projects. One of the new insulator was chosen for smoothing reactor support for 800 kV DC system in India.

International audience; We present technological building blocks and concepts under study which could ease the build-up of future THz remote sensing and communication systems. Critical issues regarding such systems mainly rely on the availability of sensitive and compact detectors together with powerful, large bandwidth and versatile sources.

The domain wall response under constant external magnetic fields reveals a complex behavior where sample disorder plays a key role. Furthermore, the response to alternating magnetic fields has only been explored in limited cases and analyzed in terms of the constant field solution. Here we unveil phenomena in the evolution of magnetic domain walls under the application of alternating magnetic fields within the creep regime, well beyond a small fluctuation limit of the domain wall position. Magnetic field pulses were applied in ultrathin ferromagnetic films with perpendicular anisotropy, and the resulting domain wall evolution was characterized by polar magneto-optical Kerr effect microscopy. Whereas the dc characterization is well predicted by the elastic interface model, striking unexpected features are observed under the application of alternating square pulses: Magneto-optical images show that after a characteristic number of cycles, domain walls evolve toward strongly distorted shapes concomitantly with a modification of domain area. The morphology of domain walls is characterized with a roughness exponent when possible and contrasted with alternative observables which are more suitable for the characterization of this transient evolution. The final stationary convergence as well as the underlying physics is discussed. Fil: Domenichini, Pablo Exequiel. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Física; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; Argentina Fil: Quinteros, Cynthia Paula. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología - Nodo Bariloche | Comisión Nacional de Energía Atómica. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología - Nodo Bariloche; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina. University of Groningen; Países Bajos Fil: Granada, Mara. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología - Nodo Bariloche | Comisión Nacional de Energía Atómica. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología - Nodo Bariloche; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina Fil: Collin, S.. Centre National de la Recherche Scientifique; Francia Fil: George, J. M.. Centre National de la Recherche Scientifique; Francia Fil: Curiale, Carlos Javier. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Oficina de Coordinacion Administrativa Ciudad Universitaria. Unidad Ejecutora Instituto de Nanociencia y Nanotecnologia. Unidad Ejecutora Instituto de Nanociencia y Nanotecnologia - Nodo Bariloche | Comision Nacional de Energia Atomica. Unidad Ejecutora Instituto de Nanociencia y Nanotecnologia. Unidad Ejecutora Instituto de Nanociencia y Nanotecnologia - Nodo Bariloche.; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Área de Energía Nuclear. Instituto Balseiro; Argentina. Universidad Nacional de Cuyo; Argentina Fil: Bustingorry, Sebastian. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Oficina de Coordinacion Administrativa Ciudad Universitaria. Unidad Ejecutora Instituto de Nanociencia y Nanotecnologia. Unidad Ejecutora Instituto de Nanociencia y Nanotecnologia - Nodo Bariloche | Comision Nacional de Energia Atomica. Unidad Ejecutora Instituto de Nanociencia y Nanotecnologia. Unidad Ejecutora Instituto de Nanociencia y Nanotecnologia - Nodo Bariloche.; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina Fil: Capeluto, Maria Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Física; Argentina Fil: Pasquini, Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Física; Argentina

8 pages, 6 figures; International audience; We present the analysis of the spin signals obtained in NiFe based metallic lateral spin valves. We exploit the spin dependent diffusive equations in both the conventional 1D analytic modeling as well as in 3D Finite Element Method simulations. Both approaches are used for extracting the spin diffusion length $l_{sf}^{N}$ and the effective spin polarization $P_{eff}$ in Py/Al, Py/Cu and Py/Au based lateral nano-structures at both $300\,K$ and $77\,K$. Both the analytic modeling and 3D Finite Element Method simulations give consistent results. Combination of both models provides a powerful tool for reliable spin transport characterization in all metallic spin valves and gives an insight into the spin/charge current and spin accumulations 3D distributions in these devices. We provide the necessary ingredients to develop the 3D finite element modeling of diffusive spin transport.

International audience; Due to the difficulty of growing high-quality semiconductors on ferromagnetic metals, the study of spin diffusion transport in Si was limited to lateral geometry devices. In this work, by using an ultrahigh-vacuum wafer-bonding technique, we have successfully fabricated metal–semiconductor–metal CoFeB/MgO/Si/Pt vertical structures. We hereby demonstrate pure spin-current injection and transport in the perpendicular current flow geometry over a distance larger than 2 μm in n-type Si at room temperature. In those experiments, a pure propagating spin current is generated via ferromagnetic resonance spin pumping and converted into a measurable voltage by using the inverse spin Hall effect occurring in the top Pt layer. A systematic study varying both Si and MgO thicknesses reveals the important role played by the localized states at the MgO–Si interface for the spin-current generation. Proximity effects involving indirect exchange interactions between the ferromagnet and the MgO–Si interface states appears to be a prerequisite to establishing the necessary out-of-equilibrium spin population in Si under the spin-pumping action.

Gray tin, also known as $\ensuremath{\alpha}$-Sn, can be turned into a three-dimensional topological insulator (3D-TI) by strain and finite-size effects. Such room-temperature 3D-TI is peculiarly interesting for spintronics due to the spin-momentum locking along the Dirac cone (linear dispersion) of the surface states. Angle-resolved photoemission spectroscopy (ARPES) has been used to investigate the dispersion close to the Fermi level in thin (001)-oriented epitaxially strained films of $\ensuremath{\alpha}$-Sn for different film thicknesses as well as for different capping layers (Al, ${\mathrm{AlO}}_{x}$, and MgO). Indeed a proper capping layer is necessary to be able to use $\ensuremath{\alpha}$-Sn surface states for spintronic applications. In contrast with free surfaces or surfaces coated with Ag, coating the $\ensuremath{\alpha}$-Sn surface with Al or ${\mathrm{AlO}}_{x}$ leads to a drop in the Fermi level below the Dirac point, and an important consequence for electronic transport is the presence of bulk states at the Fermi level. $\ensuremath{\alpha}$-Sn films coated by ${\mathrm{AlO}}_{x}$ are studied by electrical magnetotransport: Despite magnetotransport properties of the bulk electronic states of the ${\mathrm{\ensuremath{\Gamma}}}_{8}$ band playing an important role as suggested by ab initio calculations, there is clear evidence of surface states revealed by Shubnikov--de Haas oscillations corresponding to the ARPES observation.

Materials with perpendicular magnetic anisotropy (PMA) are of great interest as they have potential applications in high-density non-volatile memories, spin logic devices, and other spintronics applications. To attain perpendicular anisotropy, a number of material systems have been explored as ferromagnetic electrodes. Here, we use (Co/Pt)-multilayered films with PMA covered by a gold spacer-layer to induce the perpendicular magnetization in a ferromagnetic layer of cerium oxide and to control the reversible switching of its magnetization. The origin of the room-temperature ferromagnetism observed in nanocrystalline cerium oxide films remains controversial, but their wide energy band-gap and their transparency to visible light attracts attention for possible applications in magneto-optical devices. A weak magnetic stray field of 40 Oe emanates from the (Co/Pt)-multilayered film and permeates the gold spacer layer. Using a simple micromagnetic model based on the Stoner–Wohlfarth magnetization mechanism, the strength of the magnetic coupling between the ferromagnetic layers is estimated to be 18 μJ m−2. This magnetic coupling, which is almost independent of temperature, is sufficient to promote the reversible switching of perpendicular magnetization states in the field range of a only few hundred Oersteds at room temperature.

The development of multifunctional materials that combine optical transparency to room-temperature magnetism is still a great challenge. Here, we present an investigation on the room-temperature ferromagnetism of ceria (CeO 2) nanocrystalline films integrated to cobalt and platinum multilayered films (Co/Pt-ML) with perpendicular magnetic anisotropy (PMA). The magnetic coupling between Co/Pt-ML and CeO 2 films spaced by Pt interlayers with different thicknesses (from 3 nm to 20 nm) enable stabilization and tuning of PMA along with the stacking at remanence. CeO 2 films on the Co/Pt-ML films exhibit domain structures consisting of nonconnected labyrinthine patterns dominated by protruding fingers similar to that of individual Co/Pt-ML films. Our present results demonstrate that the PMA of Co/Pt-ML films can be used to exploit the room-temperature ferromagnetism of transparent CeO 2 films and their multifunctionalities for emerging transparent electronics and spintronics such as high-density magnetic devices.The development of multifunctional materials that combine optical transparency to room-temperature magnetism is still a great challenge. Here, we present an investigation on the room-temperature ferromagnetism of ceria (CeO 2) nanocrystalline films integrated to cobalt and platinum multilayered films (Co/Pt-ML) with perpendicular magnetic anisotropy (PMA). The magnetic coupling between Co/Pt-ML and CeO 2 films spaced by Pt interlayers with different thicknesses (from 3 nm to 20 nm) enable stabilization and tuning of PMA along with the stacking at remanence. CeO 2 films on the Co/Pt-ML films exhibit domain structures consisting of nonconnected labyrinthine patterns dominated by protruding fingers similar to that of individual Co/Pt-ML films. Our present results demonstrate that the PMA of Co/Pt-ML films can be used to exploit the room-temperature ferromagnetism of transparent CeO 2 films and their multifunctionalities for emerging transparent electronics and spintronics such as high-density mag...

We investigate the influence of the MgO growth process on the bias dependence of the electrical spin injection from a Co-Fe-B=MgO spin injector into a GaAs-based light-emitting diode (spin LED). With this aim, textured MgO tunnel barriers are fabricated either by sputtering or molecular-beam-epitaxy (MBE) methods. For the given growth parameters used for the two techniques, we observe that the circular polarization of the electroluminescence emitted by spin LEDs is rather stable as a function of the injected current or applied bias for the samples with sputtered tunnel barriers, whereas the corresponding circular polarization decreases abruptly for tunnel barriers grown by MBE. We attribute these different behaviors to the different kinetic energies of the injected carriers linked to differing amplitudes of the parasitic hole current flowing from GaAs to Co-Fe-B in both cases.

This paper presents the results of studies carried out on RTV rubber pre-coated toughened glass insulators intended for use in polluted conditions. RTV pre-coated toughened glass insulators have been developed which are coated during manufacture to produce a highly adherent and uniform layer of hydrophobic RTV silicone rubber on the dielectric, vastly improving the lifetime and effectiveness of such a coating when compared to past practice of application of coatings on site or in-situ. Over the last 10 years a test program has been implemented with periodical sampling of RTV precoated insulator strings in service in difficult environmental conditions. The reported returns from the field highlight that the RTV pre-coated insulators are an excellent solution to solve very severe contamination flashovers. This behavior should be predicted by suitable procedures for laboratory testing of such insulators with a hydrophobic coating and the proposed Rapid Flashover test method is presented. Laboratory pollution tests showed a remarkable improvement in the pollution withstand performance of RTV pre-coated glass insulators, compared to their traditional counterparts.

We present measurements of the spin Hall effect (SHE) in AuW and AuTa alloys for a large range of W or Ta concentrations by combining experiments on lateral spin valves and ferromagnetic-resonance/spin-pumping techniques. The main result is the identification of a large enhancement of the spin Hall angle (SHA) by the side-jump mechanism on Ta impurities, with a SHA as high as $+0.5$ (i.e., $50%$) for about 10% of Ta. In contrast, the SHA in AuW does not exceed $+0.15$ and can be explained by intrinsic SHE of the alloy without significant extrinsic contribution from skew or side-jump scattering by W impurities. The AuTa alloys, as they combine a very large SHA with a moderate resistivity (smaller than $85\phantom{\rule{0.28em}{0ex}}\ensuremath{\mu}\mathrm{\ensuremath{\Omega}}\phantom{\rule{0.16em}{0ex}}\text{cm}$), are promising for spintronic devices exploiting the SHE.

International audience; This paper is aimed at the comparison of performances of different types of glass insulators in dry conditions, under different types of voltage waveforms namely DC, AC and lightning impulse voltages. It is shown that the arcing distance is the main parameter influencing the flashover voltage. However, the difference between flashover voltages for the different voltage waveforms reduces when the arcing distance of insulators is increased. A comparison between experimental results with those obtained by using the streamer criterion as well as those given by empirical formulas, is presented.

International audience; We report on the compensation of the linear anisotropy of phase in a vertical-external-cavity surface-emitting laser from 21 to 0.5 mrad with an intracavity PLZT electro-optical ceramic. It allows dynamic and accurate control of the laser linear anisotropy, as well as dynamic control of the laser polarization eigenstates. At the birefringence compensation point, we observe an elliptical polarization state with 41° of ellipticity, rotated from its initial position of 32°. The experimental observations are in close agreement with the theoretical predictions. Finally, we are able to demonstrate control of the polarization state with spin injection.

The spin–orbit coupling relating the electron spin and momentum allows for spin generation, detection and manipulation. It thus fulfils the three basic functions of the spin field-effect transistor. However, the spin Hall effect in bulk germanium is too weak to produce spin currents, whereas large Rashba effect at Ge(111) surfaces covered with heavy metals could generate spin-polarized currents. The Rashba spin splitting can actually be as large as hundreds of meV. Here we show a giant spin-to-charge conversion in metallic states at the Fe/Ge(111) interface due to the Rashba coupling. We generate very large charge currents by direct spin pumping into the interface states from 20 K to room temperature. The presence of these metallic states at the Fe/Ge(111) interface is demonstrated by first-principles electronic structure calculations. By this, we demonstrate how to take advantage of the spin–orbit coupling for the development of the spin field-effect transistor., Engineering the interaction between spin and charge is important for the creation of spintronics devices. Here, the authors show that the Rashba effect at a single crystalline Fe/Ge(111) interface produces enhanced spin-charge conversion, which could help develop a spin field-effect-transistor.

The paper gives the state-of-the-art on pre-coated ceramic insulators for transmission lines. The usage of pre-coated ceramic insulators has mainly been in coastal areas where sea salt causes flashovers of ceramic insulators. The experience to date has been very good everywhere with very few problems reported. Interest in the pre-coated insulator concept continues to be strong everywhere. The paper also provides guidelines to assist the user in the specification of pre-coated ceramic insulators.

The spin-orbit interaction couples the electrons' motion to their spin. Accordingly, passing a current in a material with strong spin-orbit coupling generates a transverse spin current (spin Hall effect, SHE) and vice-versa (inverse spin Hall effect, ISHE). The emergence of SHE and ISHE as charge-to-spin interconversion mechanisms offers a variety of novel spintronics functionalities and devices, some of which do not require any ferromagnetic material. However, the interconversion efficiency of SHE and ISHE (spin Hall angle) is a bulk property that rarely exceeds ten percent, and does not take advantage of interfacial and low-dimensional effects otherwise ubiquitous in spintronics hetero- and mesostructures. Here, we make use of an interface-driven spin-orbit coupling mechanism - the Rashba effect - in the oxide two-dimensional electron system (2DES) LaAlO3/SrTiO3 to achieve spin-to-charge conversion with unprecedented efficiency. Through spin-pumping, we inject a spin current from a NiFe film into the oxide 2DES and detect the resulting charge current, which can be strongly modulated by a gate voltage. We discuss the amplitude of the effect and its gate dependence on the basis of the electronic structure of the 2DES., Comment: Final version just published in Nature Materials. Contact author for a reprint

International audience; Remanent electrical spin injection into an InGaAs/GaAs based quantum well light emitting diode is realized by using a perpendicularly magnetized MgO/CoFeB/Ta/CoFeB/MgO spin injector. We demonstrate that the Ta interlayer plays an important role to establish the perpendicular magnetic anisotropy and the thickness of Ta interlayer determines the type of exchange coupling between the two adjacent CoFeB layers. They are ferromagnetically or antiferromagnetically coupled for a Ta thickness of 0.5 nm or 0.75 nm, respectively. A circular polarized electroluminescence (Pc) of about 10% is obtained at low temperature and at zero magnetic field. The direction of the electrically injected spins is determined only by the orientation of the magnetization of the bottom CoFeB layer which is adjacent to the MgO/GaAs interface. This work proves the critical role of the bottom CoFeB/MgO interface on the spin-injection and paves the way for the electrical control of spin injection via magnetic tunnel junction-type spin injector.

We present results on spin to charge current conversion in experiments of resonant spin pumping into the Dirac cone with helical spin polarization of the elemental topological insulator (TI) α-Sn. By angle-resolved photoelectron spectroscopy (ARPES), we first check that the Dirac cone (DC) at the α-Sn (0 0 1) surface subsists after covering Sn with Ag. Then we show that resonant spin pumping at room temperature from Fe through Ag into α-Sn layers induces a lateral charge current that can be ascribed to the inverse Edelstein effect by the DC states. Our observation of an inverse Edelstein effect length much longer than those generally found for Rashba interfaces demonstrates the potential of TIs for the conversion between spin and charge in spintronic devices. By comparing our results with data on the relaxation time of TI free surface states from time-resolved ARPES, we can anticipate the ultimate potential of the TI for spin to charge conversion and the conditions to reach it.

GeTe has been predicted to be the father compound of a new class of multifunctional materials, ferroelectric Rashba semiconductors, displaying a coupling between spin-dependent k-splitting and ferroelectricity. In this paper, we report on epitaxial Fe/GeTe(111) heterostructures grown by molecular beam epitaxy. Spin-pumping experiments have been performed in a radio-frequency cavity by pumping a spin current from the Fe layer into GeTe at the Fe ferromagnetic resonance and detecting the transverse charge current originated in the slab due to spin-to-charge conversion. Preliminary experiments indicate that a clear spin to charge conversion exists, thus unveiling the potential of GeTe for spin-orbitronics.