Topologically Tuned Obliquity of Klein-Tunnelling Charged Currents Through Graphene Electrostatically-Confined p - n Junctions

Abstract

Problem of control over Klein-tunnelling states from electrostatically-confined graphene p - n junctions has been discussed. The lack of quasi-bound states, being the states with a finite life time, in a pseudo-Dirac-fermion model for the graphene quantum dot (GQD) is theoretically predicted as inapplicability of the so-called "resonance condition" leading to an inconsistent linear system corresponding to matching conditions. Within a pseudo-Dirac-Weyl fermion model GQD, the graphene charge carriers are topologically nontrivial and can be confined by a staircase-type potential due to competition between Zak curvature and centrifugal-force actions. The predicted topological effects elucidate experimentally observed resonances created by electron beam and laser pulse in crystalline arrays of single-walled carbon nanotubes as the Klein-tunnelling resonant states in the p - n graphene junctions. We present a robust approach to fabricate stable graphene p - n junctions by fine-tuning the topological effects.

Topological Defects Created by Gamma Rays in a Carbon Nanotube Bilayer

“…In this section, we present experimental evidence to show that the Majorana modes can also be revealed through scattering on resonance states created at oblique incidence on an electrostatic barrier as a result of Klein tunneling. Klein-type tunneling is featured only in the graphene hexagonal lattice hosting fermions, whose characteristics are non-Abelian [ 55 ].…”

“…A model of the bilayer structure is shown in the upper-right corner of Figure 3 b. The split ( ) band (two-phonon Raman line with double the frequency of the defect-activated (D) peak) in the Raman spectrum of the decorated CNT bilayer on Si indicates the vibrations and of the twisted CNTs across and along the twist, respectively [ 55 ]. The environmental coefficient for the decorated CNT bilayer on Si is 0.0303 and is smaller than that of the non-decorated CNT bilayer on the hydrophobized nanoporous surface due to the lack of interactions in the direction orthogonal to the CNT axis.…”

“…Since both the environment and graphene sample are exposed to radiation and the experimental conditions and samples are not identical, it is very difficult to detect the weak contribution of radiation damage to the change in the intensity of graphene Raman bands due to the significant influence of the environment [ 53 ]. The environmental influence is revealed by scanning tunneling microscopes and transmission electron microscopy (TEM) images of carbon nanotubes, which show a mismatch between the thickness and cross-section of the rolled-up graphene sheets of single-walled carbon nanotubes [ 54 , 55 ]. To avoid this, it is necessary to utilize a large number of identical graphene samples suspended on nanoporous substrates in order to prevent the doping of graphene from the side of the substrate, which is polarized and electrified due to the impact of beams of high-energy particles on a target.…”

High sensitivity electrochemical DNA sensors for detection of somatic mutations in FFPE samples

“…The confinement is explained by the occurrence of Klein resonances as a result of Klein oblique tunneling of the massless graphene charge carriers (holes or electrons) through these graphene patches. It was proved in [20] that the Klein resonances have a topologically non-trivial origin. They exist due to non-Abelian statistics of the graphene fermions, but not due to the chirality of pseudo Dirac fermions.…”

“…Moreover, when scattering and obliquely tunneling through the environmental defects the graphene charge carriers can be confined as Klein resonances [19]. The electrostatical confinement is predicted within the topologically-nontrivial graphene model [20]. The fine tuning of the Klein resonances is a challenge.…”