Figure 2.

Rashba–Edelstein effect (REE) and inverse REE (IREE) and spin Hall effect (SHE). (a) Device sketch and measurement geometry for REE. A current source (I) is applied to the Ti/Au electrodes, and the voltage (V) is measured across the Co electrodes. Red arrows represent the accumulation of in-plane spins polarized along the x axis. The color map is the magnitude of the spin density polarized along the x axis (n_s^x) at zero magnetic field (B_x = 0 T) over the sample. The plot shows the modulation of the nonlocal resistance (R_nl) vs B_x, calculated by considering the Stoner–Wohlfarth model for the behavior of the Co contacts. The white arrows in the sketch represent the Co magnetization direction. (b) Inverse REE (IREE) measurement geometry, color map for the voltage distribution at B_x ≥ 0.3 T when contact magnetization is fully aligned with Bx, and the corresponding expected modulation of the R_nl vs B_x. (c) Measurement geometry for SHE and generation of out-of-plane polarized spin current, resulting in an accumulation of out-of-plane spins (polarized along the z axis). The color map shows the density of the out-of-plane spins (n_s) at B_x = 0 T. The plot shows the modulation of R_nl, expected from Hanle precession of the out-of-plane spins, resulting in symmetric behavior vs B_x (considering that the y component of the Co contact magnetization is oriented along with the y component of the magnetic field direction). (d) R_nl versus B_x, experimentally measured in the geometry of the REE and SHE (with I = 5 μA). The measurement is performed at 4.2 K with a charge carrier density of +1.5 × 10¹² cm^–2. The inset at the top left shows the symmetric and antisymmetric components of the signal, separately. The inset at the bottom right is the R_nl measured in IREE geometry (with I = 2 μA).