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We study the electronic structure of graphene in the presence of either sevenfolds or eightfolds by using a gauge field-theory model. The graphene sheet with topological defects is considered as a negative cone surface with infinite Gaussian curvature at the center. The density of electronic states is calculated for a single seven- and eightfold as well as for a pair of sevenfolds with different morphology. The density of states at the Fermi energy is found to be zero in all cases except two sevenfolds with translational factor $M eq 0$.
The negatively-charged silicon-vacancy (SiV$^-$) center in diamond is a promising single photon source for quantum communications and information processing. However, the centers implementation in such quantum technologies is hindered by contention s
We investigate the band structure of electrons bound on periodic curved surfaces. We have formulated Schr{o}dingers equation with the Weierstrass representation when the surface is minimal, which is numerically solved. Bands and the Bloch wavefunctio
In this paper, the electronic properties of 30{deg} twisted double bilayer graphene, which loses the translational symmetry due to the incommensurate twist angle, are studied by means of the tight-binding approximation. We demonstrate the interlayer
The results of measurements of XPS spectra and magnetic properties of graphene/Co composites prepared by adding of CoCl$_2$x6H$_2$O diluted in ethyl alcohol to highly-splitted graphite are presented. XPS Co 2p measurements show two sets of 2p$_{3/2,1
Motivated by a recent groundbreaking work of Ontaneda, we describe a sizable class of closed manifolds such that the product of each manifold in the class with the real line admits a complete metric of bounded negative sectional curvature which is an