Highly Efficient Spin-Orbit Torque Switching in Bi₂Se₃/Fe₃GeTe₂ van der Waals Heterostructures

Area of Science:

• Spintronics
• Materials Science
• Condensed Matter Physics

Background:

• Topological insulators (TIs) offer promise for spin-orbit torque (SOT) applications due to efficient charge-to-spin conversion.
• Interfacing TIs with ferromagnets can degrade TI surface states via charge transfer and hybridization.

Purpose of the Study:

• To investigate the SOT switching efficiency in an all-van der Waals (vdW) heterostructure combining a TI and a 2D ferromagnet.
• To determine the critical switching current density and SOT efficiency at the TI/ferromagnet interface.

Main Methods:

• Fabrication of Bi2Se3/Fe3GeTe2 vdW heterostructures.
• Magnetization switching detection using anomalous Hall effect and magneto-optical Kerr effect.
• SOT efficiency measurement via second harmonic Hall measurements.
• First-principles density functional theory calculations.

Main Results:

• Achieved a critical switching current density of Jc ≈ 1.2 × 10^6 A/cm^2, the lowest reported for Bi2Se3 switching of perpendicular anisotropy ferromagnets.
• Determined SOT efficiency (ξDL) in the range of 1.4–1.8, comparable to the highest values for Bi2Se3.
• Density functional theory revealed weak interlayer interactions enabling access to TI surface states with in-plane spin polarization.

Conclusions:

• All-vdW heterostructures with weak interlayer interactions enhance SOT efficiency and minimize critical current density.
• This approach facilitates direct access to topological insulator surface states for spintronic applications.
• Highlights potential for next-generation low-power nonvolatile memory and spintronic devices.