Current-induced spin polarization at the surface of metallic films: a theorem and an ab initio calculation

Abstract

The broken inversion symmetry at the surface of a metallic film (or, more generally, at the interface between a metallic film and a different metallic or insulating material) greatly amplifies the influence of the spin-orbit interaction on the surface properties. The best known manifestation of this effect is the momentum-dependent splitting of the surface state energies (Rashba effect). Here we show that the same interaction also generates a spin-polarization of the bulk states when an electric current is driven through the bulk of the film. For a semi-infinite jellium model, which is representative of metals with a closed Fermi surface, we prove as a theorem that, regardless of the shape of the confinement potential, the induced surface spin density at each surface is given by $\mathbf{S}=-\gamma \hslash \hat{\mathbf{z}}\times \mathbf{j}$, where $\mathbf{j}$ is the particle current density in the bulk, $\hat{\mathbf{z}}$ the unit vector normal to the surface, and $\gamma =\frac{\hslash }{4m{c}^2}$ contains only fundamental constants. For a general metallic solid $\gamma$ becomes a material-specific parameter that controls the strength of the interfacial spin-orbit coupling. Our theorem, combined with an {\it ab initio} calculation of the spin polarization of the current-carrying film, enables a determination of $\gamma$, which should be useful in modeling the spin-dependent scattering of quasiparticles at the interface.

5 pages, 2 figures

References in corpus (11)

• Dissipationless Quantum Spin Current at Room Temperature
• Direct electronic measurement of the spin Hall effect
• Current induced electron spin polarization in strained semiconductors
• Quasiclassical approach to the spin-Hall effect in the two-dimensional electron gas
• Generation of spin currents and spin densities in systems with reduced symmetry
• Orbital momentum Hall effect in p-doped graphane
• On the nature of steady states of spin distributions in the presence of spin-orbit interactions
• Spin-Hall Conductivity and Electric Polarization in Metallic Thin Films
• Giant Extrinsic Spin Hall Effect due to Rare-Earth Impurities
• Mesoscopic Spin-Hall Effect in 2D electron systems with smooth boundaries
• Surface states, Friedel oscillations, and spin accumulation in p-doped semiconductors

Cited by in corpus (9)

• Ballistic spin transport in the presence of interfaces with strong spin-orbit coupling
• Boundary conditions for spin and charge diffusion in the presence of interfacial spin-orbit coupling
• Spin-orbit induced equilibrium spin currents in materials
• Quantum unidirectional magnetoresistance
• Current-induced spin polarization at metallic surfaces from first-principles
• Electron Interactions in Rashba Materials
• Promoted current-induced spin polarization in inversion symmetry broken topological insulator thin films
• Quantification of interfacial spin-charge conversion in metal/insulator hybrid structures by generalized boundary conditions
• Large spin-charge interconversion induced by interfacial spin-orbit coupling in a highly conducting all-metallic system