Thermoelectric spin voltage in graphene.

Area of Science:

• Condensed Matter Physics
• Spintronics
• Thermoelectricity

Background:

• Spin caloritronics explores spin-dependent thermal effects in materials.
• The spin Seebeck effect generates spin currents from thermal gradients.
• Graphene's properties, including efficient spin transport, are relevant for spintronics.

Purpose of the Study:

• To investigate thermoelectric spin voltage generation in graphene lateral spin valves.
• To demonstrate enhanced spin voltage near the graphene charge neutrality point.
• To explore the role of hot carriers in thermoelectric spin voltage.

Main Methods:

• Utilizing a graphene lateral spin valve device.
• Applying a carrier thermal gradient across the graphene channel.
• Generating hot carriers via an applied current.
• Measuring spin voltage and spin accumulation.

Main Results:

• A significant increase in spin voltage was observed near the graphene charge neutrality point.
• The observed spin voltage arises from a thermoelectric effect analogous to a thermocouple.
• Hot carriers generated by an applied current further enhance the thermoelectric spin voltage.

Conclusions:

• Graphene lateral spin valves exhibit a substantial thermoelectric spin voltage effect.
• This effect can be tuned by carrier temperature and proximity to the charge neutrality point.
• The findings are crucial for advancing graphene spintronic devices, enabling thermal gradient-driven pure spin signals.