Proposal for Unambiguous Electrical Detection of Spin-Charge Conversion in Lateral Spin Valves

Efficient detection of spin-charge conversion is crucial for advancing our understanding of emergent phenomena in spin-orbit-coupled nanostructures. Here, we provide a proof of principle of an electrical detection scheme of spin-charge conversion that enables full disentanglement of competing spin-orbit coupling (SOC) transport phenomena in diffusive lateral channels, i.e., the inverse spin Hall effect and the spin galvanic effect. A suitable geometry in an applied oblique magnetic field is shown to provide direct access to SOC transport coefficients through a symmetry analysis of the output nonlocal resistance. The scheme is robust against tilting of the spin-injector magnetization, disorder, and spurious non-spin-related contributions to the nonlocal signal and can be used to probe spin-charge conversion effects in both spin- valve and hybrid optospintronic devices

Anisotropic Absorption of Pure Spin Currents

Spin transfer in magnetic multilayers offers the possibility of ultrafast, low-power device operation. We report a study of spin pumping in spin valves, demonstrating that a strong anisotropy of spin pumping from the source layer can be induced by an angular dependence of the total Gilbert damping parameter, α, in the spin sink layer. Using lab- and synchrotron-based ferromagnetic resonance, we show that an in-plane variation of damping in a crystalline Co50Fe50 layer leads to an anisotropic α in a polycrystalline Ni81Fe19 layer. This anisotropy is suppressed above the spin diffusion length in Cr, which is found to be 8 nm, and is independent of static exchange coupling in the spin valve. These results offer a valuable insight into the transmission and absorption of spin currents, and a mechanism by which enhanced spin torques and angular control may be realized for next-generation spintronic devices

Theory of momentum-resolved magnon electron energy loss spectra: The case of Yttrium Iron Garnet

We explore the inelastic spectra of electrons impinging in a magnetic system. The methodology here presented is intended to highlight the charge-dependent interaction of the electron beam in a STEM-EELS experiment, and the local vector potential generated by the magnetic lattice. This interaction shows an intensity $10^{-2}$ smaller than the purely spin interaction, which is taken to be functionally the same as in the inelastic neutron experiment. On the other hand, it shows a strong scattering vector dependence ($\kappa^{-4}$) and a dependence with the relative orientation between the probe wavevector and the local magnetic moments of the solid. We present YIG as a case study due to its high interest by the community

Gate-Tunable Reversible Rashba−Edelstein Effect in a Few-Layer Graphene/2H-TaS2 Heterostructure at Room Temperature

We report the observation of current-induced spin polarization, the Rashba−Edelstein effect (REE), and its Onsager reciprocal phenomenon, the spin galvanic effect (SGE), in a few-layer graphene/2H-TaS2 heterostructure at room temperature. Spin-sensitive electrical measurements unveil full spin-polarization reversal by an applied gate voltage. The observed gate-tunable charge-to-spin conversion is explained by the ideal work function mismatch between 2H-TaS2 and graphene, which allows for a strong interface-induced Bychkov−Rashba interaction with a spin-gap reaching 70 meV, while keeping the Dirac nature of the spectrum intact across electron and hole sectors. The reversible electrical generation and control of the nonequilibrium spin polarization vector, not previously observed in a nonmagnetic material, are elegant manifestations of emergent two-dimensional Dirac Fermions with robust spin-helical structure. Our experimental findings, supported by first-principles relativistic electronic structure and transport calculations, demonstrate a route to design low-power spin−logic circuits from layered materials

Electrocatalytic proton reduction by a cobalt(III) hydride complex with phosphinopyridine PN ligands

Cobalt complexes with 2-(diisopropylphosphinomethyl)pyridine (PN) ligands have been synthesized with the aim of demonstrating electrocatalytic proton reduction to dihydrogen with a well-defined hydride complex of an Earth-abundant metal. Reactions of simple cobalt precursors with 2-(diisopropylphosphino-methyl)pyridine, (PN) yield [CoII(PN)2(MeCN)][BF4]2 1, [CoIII(PN)2(H)(MeCN)][PF6]2 2 and [CoIII(PN)2(H)(Cl)][PF6] 3. Complexes 1 and 3 have been characterized crystallographically. Unusually for a bidentate PN ligand, all three exhibit geometries with mutually trans phosphorus and nitrogen ligands. Complex 1 exhibits a distorted square-pyramidal geometry with an axial MeCN ligand in a low-spin electronic state. In complexes 2 and 3, the PN ligands lie in a plane leaving the hydride trans to MeCN or chloride, respectively. The redox behavior of the three complexes has been studied by cyclic voltammetry at variable scan rates and by spectroelectrochemistry. A catalytic wave is observed in the presence of trifluoroacetic acid (TFA) at an applied potential close to the Co(II/I) couple of 1. Bulk electrolysis of 1, 2 or 3 at a potential of –1.4 V in the presence of TFA yields H2 with Faradaic yields close to 100%. Foot-of-the-wave analysis allows calculation of kcat values of 860 and 1560 M-1 s-1 for 1 and 2 measured at 0.025 and 0.030 M TFA, respectively. The catalytic performance of 1 and 2 is compared to those of related catalysts by means of Tafel plots. A catalytic mechanism is proposed in which the pyridine moiety of a PN ligand acts as a pendant proton donor following opening of the chelate ring

Sequence analysis of subunits of the membrane‐bound nitrate reductase from a denitrifying bacterium:the integral membrane subunit provides a prototype for the dihaem electron‐carrying arm of a redox loop

Three genes, narH, narJ and narl of the membrane‐bound nitrate reductase operon of the denitrifying bacterium Thiosphaera pantotropha have been identified and sequenced. The derived gene products show high sequence similarity to the equivalent (β, putative δ and γ) subunits of the two membrane‐bound nitrate reductases of the enteric bacterium Escherichia coli. AU iron‐sulphur cluster ligands proposed for the E. coliβ subunits are conserved in T. pantotropha NarH. Secondary structure analysis of NarJ suggests that this protein has a predominantly α‐helical structure. Comparison of T. pantotropha Narl wilh the b‐haembinding integral membrane subunits of the E. coli enzymes allows assignment of His‐53, His‐63, His‐186 and His‐204 (T. pantotropha Narl numbering) as b‐haem axial ligands and the construction of a three‐dimensional model of this subunit. This model, in which the two b‐haems are in different halves of the membrane bilayer, is consistent with a mechanism of energy conservation whereby electrons are moved from the periplasmic to the cytoplasmic side of the membrane via the haems. Similar movement of electrons is required in the membrane‐bound uptake hydrogenases and membrane‐bound formate dehydrogenases. We have identified two pairs of conserved histidine residues in the integral membrane subunits of these enzymes that are appropriately positioned to bind one haem towards each side of the membrane bilayer. One subunit of a hydrogenase complex involved in transfer of electrons across the cytoplasmic membrane of sulphate‐reducing bacteria has structural resemblance to Narl