Based on a first-principles approach, we present scaling rules for the band gaps of graphene nanoribbons (GNRs) as a function of their widths. The GNRs considered have either armchair or zigzag shaped edges on both sides with hydrogen passivation. Both varieties of ribbons are shown to have band gaps. This differs from the results of simple tight-binding calculations or solutions of the Dirac's equation based on them. Our ab initio calculations show that the origin of energy gaps for GNRs with armchair shaped edges arises from both quantum confinement and the crucial effect of the edges. For GNRs with zigzag shaped edges, gaps appear because of a staggered sublattice potential on the hexagonal lattice due to edge magnetization. The rich gap structure for ribbons with armchair shaped edges is further obtained analytically including edge effects. These results reproduce our ab initio calculation results very well.
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http://dx.doi.org/10.1103/PhysRevLett.97.216803 | DOI Listing |
Nanotechnology
January 2025
Department of Electrical and Computer Engineering, Nazarbayev University, Nazarbayev University, Astana, Kazakhstan, Astana, 010000, KAZAKHSTAN.
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View Article and Find Full Text PDFNano Lett
January 2025
State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China.
Material challenges are the key issue in Majorana research, where surface disorder constrains device performance. Here, we tackle this challenge by embedding PbTe nanowires within a lattice-constant-matched crystal. The wire edges are shaped by self-organized growth instead of lithography, resulting in nearly atomically flat facets along both cross-sectional and longitudinal directions.
View Article and Find Full Text PDFMaterials (Basel)
December 2024
Laboratoire de Tribologie et Dynamique des Systemes (LTDS), Ecole Centrale de Lyon, Centre National de la Recherche Scientifique, 69134 Lyon, France.
This work investigates the contact between abrasive particles and workpieces in microfinishing processes with special consideration given to the determination of unit force, unit pressure, and grain, the forces exerted by individual abrasive grains. A detailed methodology was established for measuring the contact area, penetration depth, and circumferences of grain imprints at depths corresponding to multiples of the total height of the abrasive film, represented by the parameter . The following depths were analyzed: 0.
View Article and Find Full Text PDFMaterials (Basel)
December 2024
Department of Manufacturing Techniques and Automation, Faculty of Mechanical Engineering and Aeronautics, Rzeszów University of Technology, Wincentego Pola 2, 35-959 Rzeszów, Poland.
The paper presents the results of an analysis of the effect of brushing on the edge condition of workpieces with complex geometric shapes, formed during milling, on a five-axis DMU 100 monoBLOCK machining center. A set of EN-AW 7075 aluminum alloy specimens with curvilinear edges requiring multi-axis machining was prepared. The change of edge condition after the milling process was realized using Xebec tools with flexible ceramic fibers.
View Article and Find Full Text PDFLife (Basel)
November 2024
Section of Biology, Department of Biology, Faculty of Science, Dokuz Eylül University, 35390 İzmir, Türkiye.
Although embryological studies of squamates have a long history, most groups in this large clade remain poorly studied. One such group is the family Scincidae, which consists of morphologically and ecologically diverse lizards. In this study, we describe several stages of embryonic development based on cleared and stained specimens of and .
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