Spin-Orbit Torque Phenomena in Topological Insulators

Spin-orbit torque (SOT) phenomena in topological insulators arise from the interplay between strong spin–orbit coupling and spin-momentum-locked surface states. In topological insulators, an applied charge current generates a spin current through the intrinsic spin Hall effect and surface-state conversion, exerting torques on adjacent ferromagnetic layers. These torques enable magnetisation switching at reduced current densities compared with heavy metals, promising low-power, non-volatile spintronic devices. Recent advances exploit epitaxial and sputtered growth techniques, van der Waals heterostructures and interfacial engineering to optimise spin injection efficiency and spin transparency. Electric-field gating, strain modulation and compositional tuning of Bi- and Sb-based alloys have further enhanced the spin Hall angle, while room-temperature operation in two-dimensional systems and three-dimensional heterostructures underscores the practical potential for magnetic memory, logic and neuromorphic computing platforms. The global significance lies in achieving energy-efficient data storage and processing with quantum-material advantages, paving the way for scalable spin-orbitronic technologies.

Research from Nature Portfolio

Recent studies demonstrate the versatility of topological insulators as efficient spin-current sources. In a two-dimensional van der Waals heterostructure, Bi₂Te₃ coupled to Fe₃GeTe₂ achieved room-temperature magnetisation switching at a record low current density (~2.2×10⁶ A cm⁻²) and SOT efficiency (~2.7), attributable to interfacial exchange coupling and nontrivial topology. Electric-field modulation of sputtered Bi₂Se₃ on a piezoelectric substrate revealed reversible tuning of the spin Hall angle by 600 % through combined charge doping and strain-induced Berry curvature changes. Fully sputtered BiSb topological insulator/Co–Pt multilayers exhibited an exceptional spin Hall angle (~10.7) alongside high conductivity (1.5×10⁵ Ω⁻¹ m⁻¹), confirming the feasibility of large-scale fabrication of ultralow-power SOT devices.

Spin-Orbit Torque Phenomena in Topological Insulators publication trend

The graph below shows the total number of articles in spin-orbit torque phenomena in topological insulators across all publications each year (not limited to Nature Index journals).

Technical terms

Spin-orbit torque (SOT): Torque on a ferromagnet’s magnetisation induced by a spin current generated through spin–orbit coupling.

Topological insulator (TI): Quantum material with an insulating bulk and conductive, spin-momentum-locked surface states protected by symmetry.

Spin Hall angle: Dimensionless ratio representing the efficiency of converting a charge current into a transverse spin current.

Spin transparency: Fraction of spin current transmitted across an interface into an adjacent layer without reflection or dissipation.

Spin-mixing conductance: Parameter describing the efficiency of spin-angular-momentum transfer across a nonmagnetic/ferromagnetic interface.

References

1. Room temperature energy-efficient spin-orbit torque switching in two-dimensional van der Waals Fe3GeTe2 induced by topological insulators. Nature Communications (2023).
2. Giant tunable spin Hall angle in sputtered Bi2Se3 controlled by an electric field. Nature Communications (2022).
3. Ultrahigh efficient spin orbit torque magnetization switching in fully sputtered topological insulator and ferromagnet multilayers. Scientific Reports (2022).
4. Exceptional Spin‐to‐Charge Conversion in Selective Band Topology of Bi/Bi1‐xSbx with Spintronic Singularity. Advanced Functional Materials (2023).
5. All-optical observation of giant spin transparency at the topological insulator BiSbTe1.5Se1.5/Co20Fe60B20 interface. NPG Asia Materials (2023).
6. Topological insulators for efficient spin–orbit torques. APL Materials (2021).