Negative magnetoresistance of strongly disordered two-dimensional strips in the tight-binding approximation

1991 ◽  
Vol 44 (12) ◽  
pp. 6515-6518
Author(s):  
J. F. Weisz
Keyword(s):  
Tight Binding ◽  
Negative Magnetoresistance ◽  
Two Dimensional ◽  
Tight Binding Approximation

scholarly journals Kramers Degeneracy and Spin Inversion in a Lateral Quantum Dot

Symmetry ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 2043
Author(s):  
Konstantin Pichugin ◽  
Antonio Puente ◽  
Rashid Nazmitdinov
Keyword(s):  
Quantum Dot ◽  
Tight Binding ◽  
Scattering Matrix ◽  
Effective Hamiltonian ◽  
Two Dimensional ◽  
Tight Binding Approximation ◽  
One Dimensional ◽  
Ballistic Electron ◽  
Rashba Interaction ◽  
Spin Inversion

We show that the axial symmetry of the Bychkov–Rashba interaction can be exploited to produce electron spin-flip in a circular quantum dot, without lifting the time reversal symmetry. In order to elucidate this effect, we consider ballistic electron transmission through a two-dimensional circular billiard coupled to two one-dimensional electrodes. Using the tight-binding approximation, we derive the scattering matrix and the effective Hamiltonian for the considered system. Within this approach, we found the conditions for the optimal realization of this effect in the transport properties of the quantum dot. Numerical analysis of the system, extended to the case of two-dimensional electrodes, confirms our findings. The relatively strong quantization of the quantum dot can make this effect robust against the temperature effects.

Band Structure Calculations of Two-Dimensional (2 D) Models of the Phases LiBC and CaAl2Si2

1987 ◽  
Vol 42 (7) ◽  
pp. 670-682 ◽  
Author(s):  
Rafael Ramirez ◽  
Reinhard Nesper ◽  
Hans Georg von Schnering ◽  
Michael C. Böhm
Keyword(s):  
Kinetic Energy ◽  
Tight Binding ◽  
Site Symmetry ◽  
Local Geometry ◽  
Two Dimensional ◽  
Tight Binding Approximation ◽  
Hartree Fock ◽  
Crystal Orbital ◽  
Charge Model ◽  
Self Consistent Field

The electronic structures of the phases LiBC and CaAl2Si2 have been investigated by two dimensional crystal orbital calculations. The corresponding solid-state ensembles have been separated into anionic (e.g. [BC]-, [AlSi]- , [Al2Si2]2-) and cationic substructures. The employed fragmentation is topologically related to the electron counting schemes used in the classical Zintl approach. The band structures of the anionic fragments have been determined by a semiempirical Hartree-Fock crystal orbital (CO ) Hamiltonian on the basis of the tight-binding approximation. The adopted self-consistent-field variant is an intermediate neglect of differential overlap (INDO ) scheme. The influence of the cationic substructure has been simulated by an electrostatic point-charge model. The computational formalism allows for a suitable explanation of the conformations of the anionic subunits of the studied solids. In the CaAl2Si2 model the site symmetry in the anionic substructure has been studied in larger detail. The Al atoms show a tetrahedral coordination while an inverted tetrahedron (i.e. umbrella-like structure) is realized at the more electronegative Si centers. This local geometry is stabilized by the Coulomb interaction between the anionic [Al2Si2]2- layer and the cationic substructure. The energetic sources leading to the different conformations in LiBC and CaAl2Si2 are also quantified. The observed geometric preferences are rationalized by means of an energy fragmentation into covalent resonance (kinetic energy of the electrons) and classical Coulomb elements. This energy decomposition in the planar and chair-like conformations of LiBC and CaAl2Si2 shows that the kinetic energy favours the former, the electrostatic part the latter conformation. The dimerization of two anionic substructures (CaAl2Si2 structure) is also studied by the tight-binding formalism . The observed geometric differences between intra- and interlayer bonds are satisfactorily reproduced by the semiempirical CO model.

The Electronic Spectrum of Graphene

2011 ◽  
Vol 6 (3) ◽  
pp. 71-82
Author(s):  
Arkadiy A. Kozhevnikov
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Electronic Spectrum ◽  
Periodic Potential ◽  
Energy Levels ◽  
Tight Binding ◽  
Two Dimensional ◽  
Tight Binding Approximation

Based on the tight binding approximation for the energy levels of the electron in periodic potential, the electronic spectrum is found of the two-dimensional allotrope of the carbon called graphene. The problem of finding the Landau energy levels of graphene in external magnetic field is solved

scholarly journals Relevance of weak and strong classical scattering for the giant negative magnetoresistance in two-dimensional electron gases

2021 ◽  
Vol 104 (4) ◽  
Author(s):  
B. Horn-Cosfeld ◽  
J. Schluck ◽  
J. Lammert ◽  
M. Cerchez ◽  
T. Heinzel ◽  
...  
Keyword(s):  
Negative Magnetoresistance ◽  
Two Dimensional ◽  
Dimensional Electron ◽  
Electron Gases

Electrical Transport Properties of Carbon Nanotube Metal-Semiconductor Heterojunction

2016 ◽  
Vol 15 (05n06) ◽  
pp. 1660009 ◽  
Author(s):  
Keka Talukdar ◽  
Anil Shantappa
Keyword(s):  
Electrical Transport ◽  
Nearest Neighbor ◽  
Electronic Devices ◽  
Tight Binding ◽  
Transmission Function ◽  
Topological Defects ◽  
Dynamics Simulation ◽  
Internal Stresses ◽  
Electrical Transport Properties ◽  
Tight Binding Approximation

Carbon nanotubes (CNTs) have been proved to have promising applicability in various fields of science and technology. Their fascinating mechanical, electrical, thermal, optical properties have caught the attention of today’s world. We have discussed here the great possibility of using CNTs in electronic devices. CNTs can be both metallic and semiconducting depending on their chirality. When two CNTs of different chirality are joined together via topological defects, they may acquire rectifying diode property. We have joined two tubes of different chiralities through circumferential Stone–Wales defects and calculated their density of states by nearest neighbor tight binding approximation. Transmission function is also calculated to analyze whether the junctions can be used as electronic devices. Different heterojunctions are modeled and analyzed in this study. Internal stresses in the heterojunctions are also calculated by molecular dynamics simulation.

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