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Gate-tunable anomalous Hall effect in Bernal tetralayer graphene
Hao Chen1, Arpit Arora2, Justin C W Song3
1Department of Chemistry, National University of Singapore, Singapore, Singapore.
Nature Communications
|December 1, 2023
Summary
We discovered an anomalous Hall effect in stable Bernal-stacked tetralayer graphene (BTG) devices, driven by a displacement field. This finding opens new avenues for exploring magnetic order in readily available graphene materials.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Nanotechnology
Background:
- The anomalous Hall effect (AHE) is typically associated with strong spin-orbit coupling.
- Recent studies explored AHE in artificial 2D material stacks, but these are often energetically unfavorable.
- This limits experimental accessibility and device engineering for AHE research.
Purpose of the Study:
- To investigate the possibility of observing AHE in a stable and energetically favorable graphene configuration.
- To explore the underlying mechanisms and characteristics of AHE in this new material system.
- To establish Bernal-stacked tetralayer graphene (BTG) as a viable platform for studying intrinsic non-reciprocal responses.
Main Methods:
- Fabrication and characterization of Bernal-stacked tetralayer graphene (BTG) devices.
- Application of displacement fields to tune electronic properties.
- Measurement of the anomalous Hall effect (AHE) at varying carrier densities and temperatures.
Main Results:
- Observation of AHE in BTG, switchable by a displacement field and prominent at low carrier densities.
- Correlation of AHE onset with a metal-to-broken-isospin transition, suggesting an orbital origin of ferromagnetism.
- Unconventional hysteresis with step-like anomalous Hall plateaus observed at low densities, persisting to tens of kelvin.
Conclusions:
- Bernal-stacked tetralayer graphene (BTG) exhibits a robust anomalous Hall effect (AHE) without relying on strong spin-orbit coupling.
- BTG represents a stable, readily available, and energetically favorable platform for exploring magnetic order and non-reciprocal transport phenomena.
- This work expands the scope of materials for realizing intrinsic non-reciprocal responses in condensed matter physics.
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