Visualizing Tailored Spin Phenomena in a Reduced‐Dimensional Topological Superlattice

Abstract

Hall effect (SHE) and the Rashba-Edelstein effect (REE), [1,2] or vice versa. Emergent topological quantum materials, including topological insulators (TIs), [3-6] Dirac semimetals, [7] and Weyl metals [8-11]-as the key core of quantum material familieshave been compelling due to their order of magnitudes larger charge-to-spin conversion efficiencies compared to those in heavy metals. [12,13] While the spin-to-charge (SCC) efficiencies of most 3D TIs with a single surface state remain moderate, [14,15] the convergence of multiple nontrivial topological phases in one material, such as dual topological insulators, may suggest a new route for designing TI-based quantum materials. [16] Protected by both mirror symmetry and time reversal invariant symmetry, dual TIs would exhibit a high SCC efficiency benefiting from synergistic contributions of the coexisting TI phases. One prototypical example is (Bi 2-Bi 2 Se 3) N topological superlattices (N is the repeating unit number), categorized as one of an infinitely adaptive TI family series consisting of alternating one bismuth bilayer (Bi BL) and one quintuple bismuth selenide layer (Bi 2 Se 3 QL). [17] In

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

“…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.…”

“…The AS DEP CEMS-spectrum (Figure 3b) has an overall shape much well-resembling those previously observed at the interface in the 54 Fe/ 57 Fe(1 nm)/Sb 2 Te 3 /SiO 2 /Si heterostructures. [7,10] AS DEP displays a dominant central paramagnetic component, for which the hyperfine parameters do not match those of DOUB-1 in REF.…”

“…In the Fe/Sb 2 Te 3 structures that we previously discussed in refs. [7,10], pulsed laser deposition was employed to grow a ≈1 nm 57 Fe layer in direct contact with Sb 2 Te 3 , then capped by a few nm of non-CEMS sensitive 54 Fe. The main difference with the set of samples here under study (Table 1) is that 100% of isotopically enriched 57 Fe layers are used.…”

Spin-to-Charge Conversion Manipulated by Fine-Tuning the Fermi Level of Topological Insulator (Bi1–xSbx)2Te3

“…The mutual conversion between the electric and spin current is one of the most important functions of spintronic devices. − A logic device known as a magnetoelectric spin–orbit (MESO) device has been proposed that uses spin-to-charge conversion to read data bits. , A topological insulator (TI) hosts a gapless Dirac electronic state with spin-momentum locking on the surface. − The Fermi-contoured helical spin polarization of the TI surface has been demonstrated to enable the conversion between spin and charge currents through the Edelstein , and inverse Edelstein effects. − In addition, tuning the energy band structure of a TI to eliminate the contribution from the bulk state is crucial to the intrinsic quantum transport of topological surface states. , Recent research on ternary compound TI (Bi 1– x Sb x ) 2 Te 3 has demonstrated that the Dirac surface carriers can become enhanced and tunable compared with the bulk carrier contribution. − Spin polarization in the conduction of the (Bi 1– x Sb x ) 2 Te 3 topological surface state has been demonstrated , to be an attractive way to find a material candidate with improved spin-to-charge conversion, but an important question remains unsolved in this case. Does the topological surface state alone produce the maximum efficiency of the spin-to-charge conversion?…”

Unconventional Spin Pumping and Magnetic Damping in an Insulating Compensated Ferrimagnet

“…To investigate the spin dynamics in GdIG films, we conducted in‐plane FMR measurements. [ 27 ] Here the low‐frequency uniform mode, regarded as the ferromagnetic counterpart, [ 28 ] was triggered by the absorption of radiofrequency/microwave radiation, as illustrated in Figure a. Figure 2b shows the typical FMR spectra recorded as a function of the in‐plane magnetic field ( H ) at various frequencies at 300 K, from which the resonant magnetic field ( H r ) and linewidth (Δ H ) can be obtained.…”