Spin-Sensitive Epitaxial In₂Se₃ Tunnel Barrier in In₂Se₃/Bi₂Se₃ Topological van der Waals Heterostructure

Area of Science:

• Condensed Matter Physics
• Materials Science
• Spintronics

Background:

• Topological insulators (TIs) offer efficient spin-orbit torque (SOT) switching of adjacent ferromagnets (FMs).
• Current shunting through FM layers and interfacial effects degrade TI surface states in FM/TI heterostructures, increasing power consumption.

Purpose of the Study:

• To introduce an insulating barrier to prevent current shunting and preserve topological surface states.
• To demonstrate a van der Waals epitaxially grown, spin-sensitive barrier for SOT devices.

Main Methods:

• Van der Waals epitaxial growth of β-phase In2Se3 on Bi2Se3 using molecular beam epitaxy.
• Electrical detection of spin-polarized current in Bi2Se3 surface states using a Fe/In2Se3 detector.
• Density functional theory calculations to verify preservation of topological surface states.

Main Results:

• Successful epitaxial growth of β-phase In2Se3 on Bi2Se3.
• Demonstrated spin sensitivity of the Fe/In2Se3 detector contact.
• Calculations confirmed preservation of Bi2Se3 surface state dispersion and spin texture at the In2Se3/Bi2Se3 interface.

Conclusions:

• An electrically insulating, spin-sensitive barrier (In2Se3) can be epitaxially grown on a topological insulator (Bi2Se3).
• This approach preserves the topological surface states and minimizes current shunting, reducing power consumption.
• This is a key step towards efficient, fully epitaxial topological spintronic devices.