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Graphene Nanobubbles as Valley Filters and Beam Splitters
Mikkel Settnes1,2, Stephen R Power1,3, Mads Brandbyge1
1Center for Nanostructured Graphene (CNG), Department of Micro- and Nanotechnology Engineering, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark.
Physical Review Letters
|January 14, 2017
Summary
Strain-induced pseudomagnetic fields from graphene nanobubbles can generate valley-polarized currents without external magnetic fields. This offers a novel approach for valleytronics, enabling individual control of electron valleys for advanced electronic devices.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Nanotechnology
Background:
- Graphene's unique electronic properties stem from its two inequivalent valleys (K and K').
- Valleytronics aims to manipulate this valley degree of freedom, analogous to spintronics.
- Generating valley-polarized currents is crucial for valleytronic device functionality.
Purpose of the Study:
- To propose a method for achieving valley polarization in graphene.
- To demonstrate valley filtering and splitting using strain-induced effects.
- To explore the potential of graphene nanobubbles in valleytronics.
Main Methods:
- Utilizing strain-induced inhomogeneous pseudomagnetic fields (PMFs) in graphene.
- Employing experimentally feasible graphene nanobubbles to create localized strain.
- Simulating the real-space trajectories of K and K' electrons under these PMFs.
Main Results:
- Strain-induced PMFs act oppositely on the two valleys, breaking valley degeneracy.
- Graphene nanobubbles enable spatial separation and manipulation of valleys.
- The proposed method avoids the need for external magnetic fields or magnetic materials.
Conclusions:
- Graphene nanobubbles can serve as effective components for valley filtering and splitting devices.
- This approach offers a novel, non-magnetic route to valley polarization.
- The functionality of nanobubble-based devices can be tuned by controlling the deformation field.
