Abstract:
Efficient spin-to-charge conversion (SCC) mediated by the inverse Edelstein effect (IEE) at low-dimensional interfaces is central to the development of next-generation, ultra-low-power spin–orbit torque (SOT) devices. However, conventional Rashba interfaces inherently suffer from dual-channel helicity compensation—where concentric Fermi contours with opposing chiralities mutually cancel the Edelstein response—while pristine topological insulators (TIs) are frequently bottlenecked by parasitic bulk carrier shunting. In this work, we present unambiguous spectroscopic and transport evidence demonstrating how these long-standing efficiency barriers can be fundamentally shattered in engineered Bi bilayer/Bi2Te3 heterointerfaces synthesized via hydrogen-assisted surface reconstruction.
Through a synergy of in situ high-resolution angle-resolved photoemission spectroscopy (ARPES) and relativistic first-principles density functional theory (DFT) calculations, we unveil a profound, non-rigid band restructuring across the interface that completely decouples the active spintronic states from trivial bulk interferences. Remarkably, instead of a standard rigid energy shift, the interface undergoes a comprehensive relativistic spin-texture inversion: the active, upward-dispersing Rashba channels crossing immediate the Fermi level are predominantly hosted by the underlying Bi2Te3 valence electrons, whereas the deeper linear Dirac-cone features are overwhelmingly dominated by the topmost Bi overlayer. Meticulous momentum-space analysis demonstrates that within the overlapping energy window, a near-perfect wave-vector geometric alignment and orbital symmetry match induce a robust quantum resonance exclusively between the Dirac cone and the inner Rashba branch. This channel-selective hybridization effectively locks the inner contour with purified topological spin helicity while suppressing the outer counterpart, thereby shattering the dual-channel symmetry and eliminating helicity cancellation.
As a direct macroscopic manifestation of this micro-electronic remodeling, room-temperature ferromagnetic resonance (FMR) spin-pumping measurements deliver a colossal inverse Edelstein length of IEE~ 2.27 nm, representing a 3.5-fold enhancement over pristine Bi2Te3. This exceptional transport benchmark is supported quantitatively by an extraordinary computed effective Rashba coupling constant R ~ 1.16 eV Å and an optimal momentum-scattering time ~12.9 fs. Our findings firmly establish a novel spatial and energetic "quantum relay" framework—where the proximity of the Bi overlayer maximizes pure spin absorption while the highly asymmetric Bi2Te3 Fermi contours harvest the lateral charge current—offering an interface-driven paradigm for engineering high-performance topological spintronics.
Keywords – ARPES, Relativistic Quantum Transposition, Spin-Texture Inversion, Spin pumping, Giant Inverse Edelstein Effect