Large spin-charge interconversion induced by interfacial spin-orbit coupling in a highly conducting all-metallic system

Abstract

Spin-charge interconversion in systems with spin-orbit coupling has provided a new route for the generation and detection of spin currents in functional devices for memory and logic such as spin-orbit torque switching in magnetic memories or magnetic-state reading in spin-based logic. Disentangling the bulk (spin Hall effect) from the interfacial (inverse spin galvanic effect) contribution has been a common issue to properly quantify the spin-charge interconversion in these systems, being the case of Au paradigmatic. Here, we obtain a large spin-charge interconversion at a highly conducting Au/Cu interface which is experimentally shown to arise from the inverse spin galvanic effect of the interface and not from the spin Hall effect of bulk Au. We use two parameters independent of the microscopic details to properly quantify the spin-charge interconversion and the spin losses due to the interfacial spin-orbit coupling, providing an adequate benchmarking to compare with any spin-charge interconversion system. The good performance of this metallic interface, not based in Bi, opens the path to the use of much simpler light/heavy-metal systems.

Gate-Tunable Spin Hall Effect in an All-Light-Element Heterostructure: Graphene with Copper Oxide

“…At V g = 15 V, θ SH λ s CuO x /gr = 1.80 ± 0.56 nm, which is 1 order of magnitude larger than the value at V g = 0 V (0.15 ± 0.20 nm). This is a remarkable result: while we have only low- Z elements in our material system (Cu, O, C), the value is higher than in conventional large SOC materials, such as heavy metals (0.2 nm for Pt, 0.34 nm for W) or metallic Rashba interfaces (0.3 nm for Ag/Bi, −0.17 nm for Cu/Au), and is of the same order of magnitude as in material systems such as topological insulators (2.1 nm for α-Sn), oxide 2DEGs (6.4 nm for LAO/STO), or heavy metal oxide/graphene heterostructures (1 nm for BiO x /graphene at 100 K).…”

Nonreciprocal superconducting transport and the spin Hall effect in gyrotropic structures

“…The mere presence of hybrid interfaces implies a broken reflection symmetry and indicates the existence of a polar vector perpendicular to that edge, hence the system is gyrotropic and supports SGE. In normal hybrid structures containing interfaces between materials with substantial bulk SOC, a spin-to-charge conversion due to SGE has been a topic of extensive studies, both theoretically [64,[87][88][89] and experimentally [90][91][92][93][94][95][96][97][98]. From the symmetry perspective it is irrelevant whether the SGE is mediated by SOC in the bulk of materials, comes from the surface Rashba band, or originates from the interfacial SOC and spin-flip scattering off the interface.…”

Spin‐Orbit Readout Using Thin Films of Topological Insulator Sb2Te3 Deposited by Industrial Magnetron Sputtering

“…[ 1 ] In these architectures, information is stored in a ferroelectric polarization state coupled to the magnetization direction of a ferromagnetic electrode. The magnetic state of the electrode is then read electrically using the spin‐to‐charge interconversion in either heavy metals, [ 2 ] Rashba interfaces, [ 3 ] or topological insulators. [ 4 ] In these mechanisms, the spin current produced by the ferromagnetic electrode is converted into a transverse charge current thanks to the spin orbit coupling.…”