Spintronics and pseudospintronics in graphene and topological insulators.

Area of Science:

• Condensed Matter Physics
• Materials Science

Background:

• Two-dimensional electron systems in graphene and topological insulators exhibit unique electronic properties governed by massless Dirac equations.
• These systems, while sharing similar Hamiltonians, differ significantly in their spin-orbit coupling (SOC) strengths.

Purpose of the Study:

• To review and compare research efforts in graphene and topological insulators concerning spin dynamics.
• To highlight the contrasting approaches needed for manipulating spin properties in weak vs. strong SOC environments.

Main Methods:

• Review of existing literature on spin relaxation in graphene.
• Analysis of studies on current-induced spin polarization in topological insulator surface states.
• Comparative discussion of magnetic responses and dilute-moment coupling.

Main Results:

• Graphene's weak SOC necessitates strategies for achieving long spin-relaxation times.
• Topological insulators with strong SOC show potential for large current-induced spin polarizations.
• Differences in magnetic responses and dilute-moment coupling properties are noted between the two systems.

Conclusions:

• The contrasting SOC strengths in graphene and topological insulators present distinct challenges and opportunities for spintronic applications.
• Further research is needed to fully exploit the spin properties of these two-dimensional materials.
• The study provides insights into the pseudospin analogue of giant magnetoresistance in bilayer graphene.