Large-Area Intercalated Two-Dimensional Pb/Graphene Heterostructure as a Platform for Generating Spin-Orbit Torque.

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Developing efficient charge-to-spin conversion is crucial for next-generation spintronics.
• Ultrathin heavy metal films are key components, but their synthesis and stability pose challenges.

Purpose of the Study:

• To develop a scalable platform for synthesizing air-stable ultrathin heavy metals.
• To investigate the charge-to-spin conversion properties of synthesized materials.

Main Methods:

• Confinement heteroepitaxy (CHet) was used to synthesize monolayer lead (Pb) under graphene on SiC.
• Techniques including diffraction, spectroscopy, and microscopy characterized the Pb structure.
• Spin torque ferromagnetic resonance (ST-FMR) measured charge-to-spin conversion.

Main Results:

• Air-stable, epitaxially registered monolayer Pb was successfully synthesized.
• The Pb layer formed a hexagonal superstructure with ordered domain walls.
• Graphene/Pb/ferromagnet heterostructures showed a 1.5× increase in effective field ratio, indicating enhanced charge-to-spin conversion.

Conclusions:

• Confinement heteroepitaxy provides a scalable route to air-stable ultrathin heavy metals.
• The synthesized graphene/Pb heterostructures exhibit promising properties for spintronic applications.