Controlling spin relaxation in hexagonal BN-encapsulated graphene with a transverse electric field

Area of Science:

• Condensed matter physics
• Materials science
• Spintronics

Background:

• Graphene's unique electronic properties make it a promising material for spintronics.
• Understanding spin transport in graphene is crucial for developing next-generation electronic devices.

Purpose of the Study:

• To experimentally investigate electronic spin transport in hexagonal boron nitride (h-BN) encapsulated single-layer graphene nonlocal spin valves.
• To analyze the influence of electric fields on spin relaxation times and lengths.

Main Methods:

• Fabrication of nonlocal spin valve devices using single-layer graphene encapsulated by h-BN.
• Independent control of carrier density and electric field using top and bottom gates.
• Measurement of spin relaxation times and lengths at room temperature.

Main Results:

• Achieved spin relaxation times up to 2 nanoseconds and spin relaxation lengths exceeding 12 micrometers.
• Observed a spin relaxation time anisotropy ratio τ(⊥)/τ(||) ≈ 0.75 at zero electric field.
• Demonstrated electric field tunability of this anisotropy to ≈ 0.65 at 0.7 V/nm.

Conclusions:

• The results indicate efficient spin transport in graphene nonlocal spin valves.
• The observed electric field tunability of spin relaxation anisotropy is consistent with Rashba spin-orbit coupling.
• These findings contribute to the development of spintronic devices based on graphene.