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Scale-invariant large nonlocality in polycrystalline graphene
Mário Ribeiro1,2, Stephen R Power3,4, Stephan Roche3,5
1CIC nanoGUNE, 20018, Donostia-San Sebastian, Basque Country, Spain.
Nature Communications
|December 21, 2017
Summary
Large-scale graphene exhibits scale-invariant nonlocal transport, explained by field-induced spin-filtered edge states sensitive to grain boundaries. This finding impacts the practical use of topological Hall effects in graphene-based electronics.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Nanotechnology
Background:
- Graphene's nonlocal resistances are linked to intrinsic Hall effects.
- Spin and valley degrees of freedom are key in symmetry breaking.
- Scalable graphene devices are crucial for spin- and valleytronics.
Purpose of the Study:
- Investigate scale-invariant nonlocal transport in large-scale graphene.
- Understand the mechanisms behind observed nonlocal resistances.
- Assess the impact of structural morphology on topological Hall effects.
Main Methods:
- Utilized large-scale chemical vapor deposition (CVD) graphene.
- Applied an external magnetic field to induce transport phenomena.
- Analyzed nonlocal resistance measurements to identify transport mechanisms.
Main Results:
- Observed scale-invariant nonlocal transport persisting up to millimeter scales.
- Explained results by field-induced spin-filtered edge states, not Zeeman spin Hall effect.
- Demonstrated sensitivity of nonlocal resistance to grain boundaries and polycrystalline morphology.
Conclusions:
- Topological Hall effects in large-scale graphene are imprinted by polycrystalline morphology.
- Structural morphology significantly influences nonlocal transport phenomena.
- Sensitivity to grain boundaries may limit practical applications in spin- and valleytronics.
