Electrical Spin Injection and Detection in Silicon Nanowires with Axial Doping Gradient

Area of Science:

• Spintronics
• Nanotechnology
• Condensed Matter Physics

Background:

• Miniaturization of spintronics devices necessitates understanding nanoscale phenomena.
• Quantum confinement in nanostructures reveals rich spin-dependent physics.
• The ferromagnet/semiconductor (FM/SC) interface is critical for spin injection and detection.

Purpose of the Study:

• To elucidate the effects of the FM/SC interface on electrical spin injection and detection at nanoscale.
• To investigate spin transport in silicon nanowires (NWs) with an axial doping gradient.
• To establish design guidelines for nanospintronic devices.

Main Methods:

• Utilized silicon nanowires with an inherent axial doping gradient.
• Performed two-terminal and nonlocal four-terminal lateral spin-valve measurements.
• Analyzed data with a general model of spin accumulation under electrical spin injection.

Main Results:

• A distinct correlation of decreasing spin-valve signal with increasing injector junction resistance was observed.
• Diminishing contribution of d-electrons in the ferromagnet to injected current spin polarization with increasing Schottky barrier width was identified.
• Optimal spin injection efficiency and current spin polarization depend on interface parameters.

Conclusions:

• The study demonstrates a critical window of interface parameters for optimal spin injection efficiency.
• Findings provide essential design guidelines for nanospintronic devices utilizing quasi-one-dimensional semiconductor channels.
• Understanding FM/SC interface properties is crucial for advancing nanoscale spintronics.