Spin-Hall Voltage over a Large Length Scale in Bulk Germanium.

Area of Science:

• Spintronics
• Condensed Matter Physics
• Materials Science

Background:

• The spin-Hall effect provides a route to generate spin currents.
• Germanium (Ge) is a promising material for semiconductor spintronics.

Purpose of the Study:

• To generate and detect pure spin currents in n-doped Ge.
• To investigate spin accumulation and spin diffusion in Ge.

Main Methods:

• Utilizing the spin-Hall effect to create spin current.
• Employing polar magneto-optical Kerr microscopy for spin detection.
• Conducting experiments at low temperatures.

Main Results:

• Achieved a uniform pure spin current in an epitaxial n-doped Ge channel.
• Demonstrated large spin density (up to 400 μm⁻³) at Ge channel edges.
• Observed a linear decrease in spin density over tens of micrometers, indicating a long spin diffusion length.
• Showcased a slower spin density decay compared to III-V semiconductors.

Conclusions:

• Established a method for generating significant spin accumulation in Ge.
• Highlighted Ge's potential for long-range spin transport.
• Laid the groundwork for multiterminal spintronic devices utilizing Ge.