Tight-binding model study of the evolution of G-peak in monolayer graphene

2017 ◽  
Author(s):  
Sivabrata Sahu ◽  
S. K. Panda ◽  
G. C. Rout
Keyword(s):  
Tight Binding ◽  
Monolayer Graphene ◽  
Tight Binding Model ◽  
Binding Model ◽  
Model Study

Tight-Binding Model Study of Tunneling Spectra of Monolayer Graphene-on-Substrate

2018 ◽  
Vol 17 (04) ◽  
pp. 1760027 ◽  
Author(s):  
Himanshu Sekhar Gouda ◽  
Sivabrata Sahu ◽  
G. C. Rout
Keyword(s):  
Green's Functions ◽  
Green’S Functions ◽  
Tight Binding ◽  
Mean Field Approximation ◽  
Coulomb Energy ◽  
Electron Interaction ◽  
Model Parameters ◽  
Tight Binding Model ◽  
Binding Model ◽  
Model Study

We report here the theoretical model study of antiferromagnetic ordering in graphene. We propose a tight-binding model Hamiltonian describing electron hopping up to third-nearest neighbors in graphene. The Hamiltonian describing inequivalence of [Formula: see text] and [Formula: see text] sublattices in graphene-on-substrate is incorporated. The Hubbard-type repulsive Coulomb interaction is considered for both the sublattices with same Coulomb energy. The electron–electron interaction is considered within mean-field approximation with mean electron occupancies [Formula: see text] at [Formula: see text] sublattice and [Formula: see text] at [Formula: see text] site with [Formula: see text] and [Formula: see text] being the antiferromagnetic magnetizations at [Formula: see text] and [Formula: see text] sublattices, respectively. The total Hamiltonian is solved by Zubarev’s techniques of double time single particle Green’s functions. The magnetizations are calculated from the correlation functions corresponding to the respective Green’s functions. The temperature-dependent magnetizations are solved self-consistently taking suitable grid points for the electron momentum. Finally, the electron density of states (DOS) which is proportional to imaginary part of the electron Green’s functions is calculated and computed numerically at a given temperature varying different model parameters for the system. The conductance spectra show a gap near the Dirac point due to substrate-induced gap and magnetic gap, while the van Hove singularities split into eight peaks due to two different sublattice magnetizations and two different spin orientations of the electron in graphene-on-substrate.

The Tight-Binding Study of the Temperature Dependent Anti-Ferromagnetic Order in Graphene

2018 ◽  
Vol 24 (8) ◽  
pp. 5970-5974
Author(s):  
H. S Gouda ◽  
Sivabrata Sahu ◽  
G. C Rout
Keyword(s):  
Green's Functions ◽  
Green’S Functions ◽  
Tight Binding ◽  
Nearest Neighbors ◽  
Hole Doping ◽  
Tight Binding Model ◽  
Temperature Dependent ◽  
Electron Hole ◽  
Binding Model ◽  
Model Study

We propose a tight binding model study for graphene taking the electron hopping up to third-nearest-neighbors. The graphene placed on different polarized substrates introduces in-equivalences in the two sub-lattices of honeycomb unit cell of graphene. Further the electron/hole doping in graphene enhances the in-equivalence in both the sub-lattices. The Hubbard type Coulomb interaction between the electrons in both sub-lattices generates anti-ferromagnetic (AFM) order in graphene under certain conditions. Zubarev’s Green’s functions method is applied to solve the Hamiltonian. The spins of the electron in the two sub-lattices are assumed to be oriented in opposite directions giving rise to AFM order in the system. The magnetization is calculated from the Green’s functions and computed self-consistently. The effect of the presence of substrates and doping concentrations on magnetization is reported here.

Why ultrafast charge separation occurs in bulk-heterojunction organic solar cells: a multichain tight binding model study

2021 ◽  
Author(s):  
Yujuan Huang ◽  
Longlong Zhang ◽  
Yuying Hao
Keyword(s):  
Solar Cells ◽  
Quantum Efficiency ◽  
Organic Solar Cells ◽  
Charge Separation ◽  
Bulk Heterojunction ◽  
Internal Quantum Efficiency ◽  
Tight Binding ◽  
Tight Binding Model ◽  
Binding Model ◽  
Model Study

Bulk-heterojunction (BHJ) organic solar cells (OSCs) exhibit the ultrafast charge separation (UCS) ability, enables lowering the geminate charge recombination and achieving the high internal quantum efficiency. Unravelling why UCS occurs...

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