Large Tunable Spin-to-Charge Conversion Induced by Hybrid Rashba and Dirac Surface States in Topological Insulator Heterostructures

Abstract

Topological insulators (TIs) have emerged as some of the most efficient spin-to-charge convertors because of their correlated spin-momentum locking at helical Dirac surface states. While endeavors have been made to pursue large "charge-to-spin" conversions in novel TI materials using spin-torque-transfer geometries, the reciprocal process "spinto-charge" conversion, characterized by the inverse Edelstein effect length (λ IEE ) in the prototypical TI material (Bi 2 Se 3 ), remains moderate. Here, we demonstrate that, by incorporating a "second" spin-splitting band, namely, a Rashba interface formed by inserting a bismuth interlayer between the ferromagnet and the Bi 2 Se 3 (i.e., ferromagnet/Bi/Bi 2 Se 3 heterostructure), λ IEE shows a pronounced increase (up to 280 pm) compared with that in pure TIs. We found that λ IEE alters as a function of bismuth interlayer thickness, suggesting a new degree of freedom to manipulate λ IEE by engineering the interplay of Rashba and Dirac surface states. Our finding launches a new route for designing TI-and Rashba-type quantum materials for next-generation spintronic applications.

Large spin to charge conversion in the topological superconductor β−PdBi2 at room temperature

“…4(c) shows hyperbolic tangent behavior as a function of the film thickness. This dependence is quite different from that in FM/TI heterostructures as expected from the IREE [47,48] but tracks the behavior observed in heavy metals in accordance with the ISHE. This suggests that a significant amount of charge current is generated from the bulk of the alloy meaning that SOC is dominant in interconversion at room temperature, which has also been seen in other topological materials like Bi-Sb alloys [49] and WTe2 [50].…”

Visualizing Tailored Spin Phenomena in a Reduced‐Dimensional Topological Superlattice

“…It is noteworthy that all of the obtained values are still 5–7 times larger than that of pristine 3D‐TI Bi 2 Se 3 (≈0.035 nm), [ 14 ] indicating the synergistic SCC efficiency from dual TSSs. Compared with the best reported Bi‐based quantum materials as summarized in Figure 2g: λ IEE = 0.05 nm in the isolated Bi layer, [ 26 ] 0.28 nm in Bi/Bi 2 Se 3 , [ 23 ] and 0.3 nm in the sputtered Bi 2 Se 3 materials, [ 27 ] the obtained large spin‐to‐charge conversion in the TSLs indicates the key role of the reduced dimensionality and coexisting TSSs, as revealed in the ARPES results, in determining the spin‐to‐charge conversion.…”

“…[ 22 ] The Fermi velocity v F of “V”‐type upturn bands is estimated to be about 5 × 10 5 m s −1 , (see Figure S2d, Supporting Information) which is comparable to the value in the pristine Bi 2 Se 3 from our previous report. [ 23 ] In contrast to the warped hexagon in the Bi 2 Se 3 ‐terminated superlattice, the Fermi surface in the Bi 2 ‐terminated sample manifests as a hexagonal snowflake with six‐fold symmetry, which also demonstrates the perfect hetero‐epitaxy between the alternating Bi 2 Se 3 and Bi 2 layers. The energy dispersion along the direction shown in the right panel of Figure 1d presents hole‐like maximal momentum splitting at the Fermi level with Δ k F ≈ 0.5 Å −1 (see Figure S5a, Supporting Information).…”

Observation of long spin lifetime in MAPbBr3 single crystals at room temperature

“…Fermi contour [20]. These Rashba states have been studied in two-dimensional electron gas (2DEG) systems [21] and 3D topological insulators [22], showing great promise for next generation spin-to-charge transduction applications at room temperature. The recent debut of spintronic studies using hybrid metal halide (HMH) materials [23][24][25][26][27], such as the prototypical material methylammonium lead bromide (CH 3 NH 3 PbBr 3 , MAPbBr 3 ), have attracted an immense amount of research interest beyond their exciting optoelectronic properties for applications in solar cells [28][29][30][31][32], light-emitting diodes [33][34][35], lasers [36][37][38], and photodetectors [39][40][41][42] etc.…”