Coherent spin transport through a 350 micron thick silicon wafer

Area of Science:

• Solid State Physics
• Materials Science
• Spintronics

Background:

• Electron spin manipulation is crucial for next-generation electronics.
• Efficient spin transport and long spin lifetimes in semiconductors are key challenges.
• Silicon is a promising material for spintronic applications due to its compatibility with existing technology.

Purpose of the Study:

• To investigate the vertical injection, transport, and detection of spin-polarized electrons in bulk silicon.
• To measure spin coherence and determine the spin lifetime of conduction electrons in silicon.
• To establish a lower bound for the spin lifetime in silicon at cryogenic temperatures.

Main Methods:

• Utilized all-electrical methods for spin injection, transport, and detection.
• Employed spin precession measurements in a perpendicular magnetic field.
• Analyzed magnetocurrent changes from spin-valve measurements to determine spin polarization.
• Applied an exponential spin-decay model to estimate spin lifetime.

Main Results:

• Successfully injected, transported, and detected spin-polarized electrons vertically through a 350-micron silicon wafer.
• Observed high spin coherence, indicated by precession angles of at least 13π.
• Determined electron transit times via magnetic-field spacing of precession extrema.
• Established a lower bound for the conduction electron spin lifetime (T1) in silicon exceeding 500 ns at 60 K.

Conclusions:

• Vertical spin transport in bulk silicon is feasible using all-electrical methods.
• Silicon exhibits significant spin coherence at 60 K, enabling long-distance spin transport.
• The determined spin lifetime provides critical data for developing silicon-based spintronic devices.