Perfect Reflection of Chiral Fermions in Gated Graphene Nanoribbons

Abstract

We describe the results of a theoretical study of transport through gated metallic graphene nanoribbons using a nonequilibrium Green function method. Although analogies with quantum field theory predict perfect transmission of chiral fermions through gated regions in one dimension, we find perfect reflection of chiral fermions in armchair ribbons for specific configurations of the gate. This effect should be measurable in narrow graphene constrictions gated by a charged carbon nanotube.

Optimization of the polarized Klein tunneling currents in a sub-lattice: pseudo-spin filters and latticetronics in graphene ribbons

“…As a result, the electronic state is not dispersed (no backscattering) [15]. This behavior is unique to graphene and armchair graphene nanoribbons [10,16]. It is known that for a zigzag graphene nanoribbon the potential barrier completely destroys the tunneling currents [17,18].…”

“…In recent years, quasi-one-dimensional structures called nanoribbons have been obtained from graphene [29][30][31]. Particular interest is given to graphene nanoribbons with armchair edges (AGRs), which present metallic or semiconductor behavior depending on their width [32], and also an analogue of Klein tunneling [16]. An interesting and still open problem is how to use 'Klein tunneling' and the pseudo-spin polarization to control the polarized currents in a sub-lattice for technological applications.…”

Optical properties of pure graphene in various forms: a time dependent density functional theory study

“…There have been reports indicating the shape and size dependence due to the edge states and quantum connement effects has been found to have effect on the optical, electrical and magnetic properties of graphene nano-ribbons. [8][9][10][11][12][13] There have been signicant research interests on the optical properties of graphene [14][15][16][17] owing to their wide applications in photonics and optoelectronics ranging from solar cells and light-emitting devices to touch screens, photo-detectors and ultrafast lasers. Recently rst-principles calculations have identied enhanced excitonic effects on optical spectra of pure graphene 18 followed by subsequent experimental evidences.…”

Spin Controlling in Narrow Zigzag Silicon Carbon Nanoribbons by Carrier Doping

“…The key feature is the control and manipulation of the “spin” of the electron, instead of its charge that is the focus of the electronics . It is noted that the graphene nanoribbons (NRs) offer a possibility of achieving these purposes. − Hence, the graphene NRs have attracted a lot of study. − The graphene NRs are made by cutting the graphene sheets, where the edge carbon atoms are passivated by hydrogen. It was found that the graphene NRs can be either metallic or semiconducting depending on the width and structure of the edges. − Notably, the zigzag graphene NRs (graphene nanoribbons with zigzag edges) are a magnetic semiconductor with a small band gap, and have ferromagnetic ordering at each edge and their spins at each edge are antiparallel. ,− When a very strong transverse electric field is applied, the ZG NRs transform to half metal, − where only one of the spin channels conducts, while the other remains insulating, which suggests possibilities for the control and manipulation of the spin-polarized electron transport by applying electric field.…”