Observation of High Spin-to-Charge Conversion by Sputtered Bismuth Selenide Thin Films at Room Temperature

Abstract

We investigated spin-to-charge conversion in sputtered Bi43Se57/Co20Fe60B20 heterostructures with in-plane magnetization at room temperature. High spin-to-charge conversion voltage signals have been observed at room temperature. The transmission electron microscope images show that the sputtered bismuth selenide thin films are nanogranular in structure. The spin-pumping voltage decreases with an increase in the size of the grains. The inverse Edelstein effect length (λIEE) is estimated to be as large as 0.32 nm. The large λIEE is due to the spin-momentum locking and is further enhanced by quantum confinement in the nanosized grains of the sputtered bismuth selenide films. We also investigated the effect on spin-pumping voltage due to the insertion of layers of MgO and Ag. The MgO insertion layer has almost completely suppressed the spin-pumping voltage, whereas the Ag insertion layer has enhanced the λIEE by 43%.

Spin‐Charge Conversion in Fe/Au/Sb2Te3 Heterostructures as Probed By Spin Pumping Ferromagnetic Resonance

“…The two-magnon scattering (TMS) cannot be fully accounted for with the subtraction method, and it can generate an over-or under-estimation of g eff . [4,35] On the other hand, our extracted g eff value for both PRE ANN and POST ANN samples is g eff = 2.2 • 10 19 m 2 , being very well in accordance with those reported for similar heterostructures, [25][26][27][28][29][30][31][32][33][34][35][36][37][38][39] thus suggesting a negligible contribution of TMS at the Fe/Sb 2 Te 3 interfaces.…”

“…For sample POST ANN-IL we obtain λ IEE = 0.27 nm, which is in perfect agreement with the value obtained in Au/Co/Au/Sb 2 Te 3 , [4] thus demonstrating the intrinsic role played by Sb 2 Te 3 and its preserved TSS to origin such a large S2C. When compared to other 2 nd class chalcogenide-based TI, [26,[37][38][39][48][49][50][51][52][53][54] the extracted λ IEE is comparable to the highest reported so far.…”

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.…”