scholarly journals Quantum oscillations of magnetization in tight-binding electrons on a honeycomb lattice

2014 ◽  
Vol 90 (8) ◽  
Author(s):  
Keita Kishigi ◽  
Yasumasa Hasegawa
Keyword(s):  
Tight Binding ◽  
Honeycomb Lattice ◽  
Quantum Oscillations

scholarly journals Dodecagonal bilayer graphene quasicrystal and its approximants

2019 ◽  
Vol 5 (1) ◽  
Author(s):  
Guodong Yu ◽  
Zewen Wu ◽  
Zhen Zhan ◽  
Mikhail I. Katsnelson ◽  
Shengjun Yuan
Keyword(s):  
Large Scale ◽  
Lattice Mismatch ◽  
Tight Binding ◽  
Bilayer Graphene ◽  
Dominant Factor ◽  
Honeycomb Lattice ◽  
Fermi Velocity ◽  
Band Theory ◽  
Incommensurate Structures ◽  
Unfolding Method

AbstractDodecagonal bilayer graphene quasicrystal has 12-fold rotational order but lacks translational symmetry which prevents the application of band theory. In this paper, we study the electronic and optical properties of graphene quasicrystal with large-scale tight-binding calculations involving more than ten million atoms. We propose a series of periodic approximants which reproduce accurately the properties of quasicrystal within a finite unit cell. By utilizing the band-unfolding method on the smallest approximant with only 2702 atoms, the effective band structure of graphene quasicrystal is derived. The features, such as the emergence of new Dirac points (especially the mirrored ones), the band gap at $$M$$M point and the Fermi velocity are all in agreement with recent experiments. The properties of quasicrystal states are identified in the Landau level spectrum and optical excitations. Importantly, our results show that the lattice mismatch is the dominant factor determining the accuracy of layered approximants. The proposed approximants can be used directly for other layered materials in honeycomb lattice, and the design principles can be applied for any quasi-periodic incommensurate structures.

scholarly journals Ultra-high Yield On-surface Synthesis and Assembly of Circumcoronene into Chiral Electronic Kagome-honeycomb Lattice

2020 ◽  
Author(s):  
Mykola Telychko ◽  
Guangwu Li ◽  
Pingo Mutombo ◽  
Diego Soler-Polo ◽  
Xinnan Peng ◽  
...  
Keyword(s):  
Density Functional ◽  
Large Scale ◽  
Tight Binding ◽  
Cascade Reactions ◽  
High Yield ◽  
Honeycomb Lattice ◽  
Scale Production ◽  
Methyl Radical ◽  
Synthetic Strategy ◽  
Temperature Scanning

On-surface synthesis has revealed remarkable potential in the fabrication of a plethora of elusive nanographenes with tailored structural, electronic and magnetic properties unattainable by conventional wet-chemistry synthesis. Unfortunately, surface-assisted synthesis often involves multiple-step cascade reactions with competing pathways, leading to the formation of a diversity of products with limited yield, which reduces its feasibility towards the large-scale production for future technological applications. Here, we devise a new on-surface synthetic strategy for the ultra-high yield synthesis of a hexagonal nanographene with six zigzag edges, namely circumcoronene on Cu(111) via surfaceassisted intramolecular dehydrogenation of the rationally-designed precursor molecule, followed by methyl radical-radical coupling and aromatization. An elegant electrostatic interaction between circumcoronene and Cu(111) drives their self-organization into an extended superlattice, as revealed by bond-resolved low-temperature scanning probe microscopy and spectroscopy measurements. Density functional theory and tight-binding calculations reveal that unique hexagonal zigzag topology of circumcoronenes, along with their periodic electrostatic landscape confines two-dimensional (2D) electron gas in Cu(111) surface into chiral electronic Kagome-honeycomb lattice with two emergent electronic flat bands. Our findings open up a new route for the high-yield fabrication of elusive nanographenes with zigzag topologies and their novel 2D superlattices with possible nontrivial electronic properties towards their future technological applications.

scholarly journals Ultra-high Yield On-surface Synthesis and Assembly of Circumcoronene into Chiral Electronic Kagome-honeycomb Lattice

2020 ◽  
Author(s):  
Mykola Telychko ◽  
Guangwu Li ◽  
Pingo Mutombo ◽  
Diego Soler-Polo ◽  
Xinnan Peng ◽  
...  
Keyword(s):  
Density Functional ◽  
Large Scale ◽  
Tight Binding ◽  
Cascade Reactions ◽  
High Yield ◽  
Honeycomb Lattice ◽  
Scale Production ◽  
Methyl Radical ◽  
Synthetic Strategy ◽  
Temperature Scanning

On-surface synthesis has revealed remarkable potential in the fabrication of a plethora of elusive nanographenes with tailored structural, electronic and magnetic properties unattainable by conventional wet-chemistry synthesis. Unfortunately, surface-assisted synthesis often involves multiple-step cascade reactions with competing pathways, leading to the formation of a diversity of products with limited yield, which reduces its feasibility towards the large-scale production for future technological applications. Here, we devise a new on-surface synthetic strategy for the ultra-high yield synthesis of a hexagonal nanographene with six zigzag edges, namely circumcoronene on Cu(111) via surfaceassisted intramolecular dehydrogenation of the rationally-designed precursor molecule, followed by methyl radical-radical coupling and aromatization. An elegant electrostatic interaction between circumcoronene and Cu(111) drives their self-organization into an extended superlattice, as revealed by bond-resolved low-temperature scanning probe microscopy and spectroscopy measurements. Density functional theory and tight-binding calculations reveal that unique hexagonal zigzag topology of circumcoronenes, along with their periodic electrostatic landscape confines two-dimensional (2D) electron gas in Cu(111) surface into chiral electronic Kagome-honeycomb lattice with two emergent electronic flat bands. Our findings open up a new route for the high-yield fabrication of elusive nanographenes with zigzag topologies and their novel 2D superlattices with possible nontrivial electronic properties towards their future technological applications.

scholarly journals Zero modes of tight-binding electrons on the honeycomb lattice

2006 ◽  
Vol 74 (3) ◽  
Author(s):  
Yasumasa Hasegawa ◽  
Rikio Konno ◽  
Hiroki Nakano ◽  
Mahito Kohmoto
Keyword(s):  
Tight Binding ◽  
Honeycomb Lattice ◽  
Zero Modes

scholarly journals Ultrahigh-yield on-surface synthesis and assembly of circumcoronene into a chiral electronic Kagome-honeycomb lattice

2021 ◽  
Vol 7 (3) ◽  
pp. eabf0269 ◽  
Author(s):  
Mykola Telychko ◽  
Guangwu Li ◽  
Pingo Mutombo ◽  
Diego Soler-Polo ◽  
Xinnan Peng ◽  
...  
Keyword(s):  
Density Functional ◽  
Tight Binding ◽  
Cascade Reactions ◽  
High Yield ◽  
Metallic Surface ◽  
Honeycomb Lattice ◽  
Methyl Radical ◽  
Functional Theory ◽  
Radical Coupling ◽  
Dimensional Electron Gas

On-surface synthesis has revealed remarkable potential in the fabrication of atomically precise nanographenes. However, surface-assisted synthesis often involves multiple-step cascade reactions with competing pathways, leading to a limited yield of target nanographene products. Here, we devise a strategy for the ultrahigh-yield synthesis of circumcoronene molecules on Cu(111) via surface-assisted intramolecular dehydrogenation of the rationally designed precursor, followed by methyl radical-radical coupling and aromatization. An elegant electrostatic interaction between circumcoronenes and metallic surface drives their self-organization into an extended superlattice, as revealed by bond-resolved scanning probe microscopy measurements. Density functional theory and tight-binding calculations reveal that unique hexagonal zigzag topology of circumcoronenes, along with their periodic electrostatic landscape, confines two-dimensional electron gas in Cu(111) into a chiral electronic Kagome-honeycomb lattice with two emergent electronic flat bands. Our findings open up a new route for the high-yield fabrication of elusive nanographenes with zigzag topologies and their superlattices with possible nontrivial electronic properties.

scholarly journals The Graphene Field Effect Transistor Modeling Based on an Optimized Ambipolar Virtual Source Model for DNA Detection

2021 ◽  
Vol 11 (17) ◽  
pp. 8114
Author(s):  
Moaazameh Akbari ◽  
Mehdi Jafari Shahbazzadeh ◽  
Luigi La Spada ◽  
Alimorad Khajehzadeh
Keyword(s):  
Field Effect ◽  
Field Effect Transistors ◽  
Lattice Structure ◽  
Dna Detection ◽  
Tight Binding ◽  
Clinical Diagnostics ◽  
Least Square ◽  
Compact Model ◽  
Honeycomb Lattice ◽  
Virtual Source

The graphene-based Field Effect Transistors (GFETs), due to their multi-parameter characteristics, are growing rapidly as an important detection component for the apt detection of disease biomarkers, such as DNA, in clinical diagnostics and biomedical research laboratories. In this paper, the non-equilibrium Green function (NEGF) is used to create a compact model of GFET in the ballistic regime as an important building block for DNA detection sensors. In the proposed method, the self-consistent solutions of two-dimensional Poisson’s equation and NEGF, using the nearest neighbor tight-binding approach on honeycomb lattice structure of graphene, are modeled as an efficient numerical method. Then, the eight parameters of the phenomenological ambipolar virtual source (AVS) circuit model are calibrated by a least-square curve-fitting routine optimization algorithm with NEGF transfer function data. At last, some parameters of AVS that are affected by induced charge and potential of DNA biomolecules are optimized by an experimental dataset. The new compact model response, with an acceptable computational complexity, shows a good agreement with experimental data in reaction with DNA and can effectively be used in the plan and investigation of GFET biosensors.

Effect of impurity doping on AFM magnetization in graphene: A tight-binding model approach

2017 ◽  
Vol 06 (04) ◽  
pp. 1850001
Author(s):  
Sivabrata Sahu ◽  
Himanshu Sekhar Gouda ◽  
G. C. Rout
Keyword(s):  
Tight Binding ◽  
Mean Field ◽  
Field Approximation ◽  
Mean Field Approximation ◽  
Function Technique ◽  
Honeycomb Lattice ◽  
Coulomb Interactions ◽  
Binding Model ◽  
Impurity Doping ◽  
Spin Moments

We report here a tight-binding theoretical study of anti-ferromagnetism in graphene taking electron hopping up to third nearest neighbors. The graphene on substrate introduces inequivalence in the two sublattices of the honeycomb lattice. The on-site Coulomb interactions at two sublattices of graphene are treated within mean-field approximation and the electron occupancies at two sublattices include spin moments in opposite directions giving rise to anti-ferromagnetism in graphene. The AFM sublattice magnetizations are calculated by using Zubarev’s Green’s function technique and computed self-consistently for different ranges of Coulomb potential, substrate-induced gap and impurity concentrations. It is observed that [Formula: see text]-site magnetization is suppressed by [Formula: see text]-site impurity concentration, while [Formula: see text]-site magnetization remains unaffected. Similar effect has been observed at [Formula: see text]-site when doped with pentavalent dopant, while [Formula: see text]-site magnetization remains unaffected. Furthermore, substrate-induced AFM gap has also been observed at different ranges of temperature.

scholarly journals Energy gap of tight-binding electrons on generalized honeycomb lattice

2008 ◽  
Vol 132 ◽  
pp. 012005 ◽  
Author(s):  
Keita Kishigi ◽  
Ryuichi Takeda ◽  
Yasumasa Hasegawa
Keyword(s):  
Energy Gap ◽  
Tight Binding ◽  
Honeycomb Lattice
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