Ultra‐High Spin Hall Angle in Sputtered Sb ₂ Te ₃ Topological Insulators via Pt Interfacial Engineering

ABSTRACT Topological insulators (TIs) attract great interest in spintronics for their highly efficient charge‐to‐spin conversion. Sb 2 Te 3 is especially promising due to its thermal stability up to 450 °C, which aligns well with semiconductor processing temperatures (350–400 °C) and makes it suitable for TI‐based magnetic random‐access memory (MRAM). This work tackles key integration challenges—such as stoichiometry, interface diffusion, and thermal degradation—by optimizing magnetron sputtering of Sb 2 Te 3 on Si/SiO 2 at 350°C, yielding films with excellent crystallinity and smooth surfaces. A 1.5‑nm Pt interlayer was introduced between Sb 2 Te 3 and FeNi to suppress magnetic proximity effects and interfacial intermixing, thereby enhancing spin‐orbit torque (SOT) efficiency. Second‐harmonic Hall measurements show a record SOT efficiency with a spin Hall angle of 30.42, outperforming conventional heavy metals (e.g., Pt, W) by over two orders of magnitude and previously reported vapor‐deposited Sb 2 Te 3 . This study highlights how interface engineering can dramatically improve charge‐spin conversion without compromising scalability, offering a practical route toward efficient SOT‐MRAM and guiding future spintronic designs.e