CVD Bilayer Graphene Spin Valves with 26 μm Spin Diffusion Length at Room Temperature

Area of Science:

• Spintronics
• Materials Science
• Condensed Matter Physics

Background:

• Graphene-based spintronic devices offer promising applications.
• Previous fabrication methods for bilayer graphene (BLG) devices faced limitations.
• Improving spin transport properties in graphene at room temperature is crucial.

Purpose of the Study:

• To fabricate high-performance inverted spin-valve devices using chemical vapor deposition (CVD)-grown bilayer graphene (BLG).
• To enhance device performance by employing a polydimethylsiloxane droplet-assisted full-dry transfer technique.
• To characterize the spin transport properties of BLG devices at room temperature.

Main Methods:

• Fabrication of inverted spin-valve devices using CVD-grown BLG.
• Utilized a polydimethylsiloxane droplet-assisted full-dry transfer technique for device fabrication.
• Performed gate-dependent Hanle measurements to assess spin properties.

Main Results:

• Achieved more than a doubling in device performance at room temperature compared to existing BLG spin valves.
• Demonstrated spin lifetimes up to 5.8 ns and spin diffusion lengths up to 26 μm at room temperature.
• Measured charge carrier mobility of approximately 24 000 cm²(V s)^-1 in the best performing device.
• CVD-grown BLG exhibited comparable room temperature spin transport properties to single-layer graphene.

Conclusions:

• The polydimethylsiloxane droplet-assisted full-dry transfer technique significantly improves BLG spin-valve performance.
• CVD-grown BLG is a viable material for high-performance room temperature spintronic devices.
• BLG demonstrates excellent spin transport properties, rivaling those of single-layer graphene.