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Fabrication of Gate-tunable Graphene Devices for Scanning Tunneling Microscopy Studies with Coulomb Impurities
Published on: July 24, 2015
Fully valley-polarized electron beams in graphene
J L Garcia-Pomar1, A Cortijo, M Nieto-Vesperinas
1Instituto de Ciencia de Materiales de Madrid, CSIC, Cantoblanco, Madrid, Spain.
Physical Review Letters
|July 23, 2008
Summary
We propose a novel graphene device for valleytronics, enabling controllable splitting or collimation of valley-polarized currents. This breakthrough utilizes trigonal warping and negative refraction for advanced electronic applications.
Area of Science:
- Condensed matter physics
- Materials science
- Nanotechnology
Background:
- Valleytronics in graphene offers potential for novel electronic devices.
- Controlling valley polarization is crucial for harnessing this potential.
- Existing methods lack precise control over valley-polarized currents.
Purpose of the Study:
- To propose a new device for breaking valley degeneracy in graphene.
- To achieve fully valley-polarized currents that can be split or collimated.
- To demonstrate experimental controllability of valley-polarized beams.
Main Methods:
- Combining negative refraction with valleytronics in graphene.
- Utilizing the specular Fermi surface shape (trigonal warping) induced by gate voltage.
- Employing a gate-voltage-controlled n-p-n junction in a graphene transistor.
Main Results:
- The device acts as a valley beam splitter, separating currents by valley.
- The device functions as a collimator, focusing valley-polarized beams.
- Experimental controllability is achieved by tuning the gate voltage.
Conclusions:
- The proposed device offers a novel way to control valley polarization in graphene.
- This work paves the way for advanced valleytronics applications.
- The findings are supported by an optical analogy with photonic crystals.
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