Mesoscopic Interference of Rotated Spins in Graphene Coupled to High-Spin-Orbit-Coupling Substrates

Area of Science:

• Condensed Matter Physics
• Materials Science
• Spintronics

Background:

• Graphene's electronic properties are tunable, making it a candidate for spintronic applications.
• Spin-orbit coupling (SOC) is crucial for manipulating electron spins in materials.
• Understanding spin interference in mesoscopic systems is key for device development.

Purpose of the Study:

• To investigate spin rotation in graphene when interfaced with high SOC materials (Co and WSe2).
• To characterize the mesoscopic and stochastic nature of spin interference using weak antilocalization (WAL).
• To explore the impact of gate voltage on spin rotation and antilocalization effects.

Main Methods:

• Utilizing weak antilocalization (WAL) as a probe for spin rotation.
• Measuring differential conductance to identify zero-bias peaks (ZBAs).
• Applying magnetic fields and gate voltages to tune and suppress WAL effects.

Main Results:

• Spin interference in graphene exhibits highly stochastic (nonself-averaging) behavior in the mesoscopic limit.
• A zero-bias anomaly (ZBA) in differential conductance, indicative of WAL, was observed at low temperatures.
• The ZBA showed stochastic variations with gate voltage and was suppressed by magnetic fields and increasing temperature.

Conclusions:

• Spin rotation in mesoscopic graphene systems with strong SOC is fundamentally nonself-averaged.
• External gating significantly impacts spin rotation details, providing a mechanism for modulation.
• This research offers insights for controlling spin currents in future spintronic devices.