Tight-binding calculation of giant magnetoresistance in Co/Cu/Co spin valves with layer-dependent scattering

1997 ◽  
Vol 475 ◽  
Author(s):  
E.Yu. Tsymbal ◽  
D.G. Pettifor
Keyword(s):  
Giant Magnetoresistance ◽  
Electronic Band Structure ◽  
Outer Boundary ◽  
Energy Levels ◽  
Tight Binding ◽  
Spin Valve ◽  
Mean Free Path ◽  
Electronic Band ◽  
Tight Binding Approximation ◽  
Atomic Energy Levels

ABSTRACTWe have modelled the effects of bulk, outer-boundary, and interfacial disorder on conductivity and giant magnetoresistance (GMR) in Co101010/ trilayer taking into account its realistic electronic band structure. Calculations were performed using our model [E. Yu. Tsymbal and D.G. Pettifor, Phys. Rev. B 54 (1996) 15314] extended to the systems with two-dimensional periodicity and layer-dependent disorder. The model is based on the Kubo-Greenwood formula and spin-independent disorder in the on-site atomic energy levels, reflecting the scattering by defects, within an spd tight-binding approximation. Exploring the contributions to conductivity from different layers, we find that the influence on GMR of the boundary and interfacial scattering is similar to the bulk scattering, because the conductivity is non-local and the thicknesses of films are comparable to the electronic mean free path. Increasing the spin-independent disorder causes a decrease of GMR in the spin-valve for both interfacial, outer-boundary and bulk mechanisms of scattering. We have also investigated the effect of outer-boundary and interfacial paramagnetic Co layers on GMR in the trilayer. We find that the GMR, in this case, is strongly reduced due to the strong spin-independent scattering at the paramagnetic layers and hybridization of d states of the paramagnetic layers with the sp bands.

ELECTRONIC BAND STRUCTURE OF CARBON NANOTUBES WITH QUINOID STRUCTURE

2013 ◽  
Vol 27 (25) ◽  
pp. 1350179
Author(s):  
NGUYEN NGOC HIEU ◽  
NGUYEN PHAM QUYNH ANH
Keyword(s):  
Carbon Nanotubes ◽  
Carbon Nanotube ◽  
Band Structure ◽  
Electronic Band Structure ◽  
Tight Binding ◽  
Electronic Energy ◽  
Electronic Band ◽  
Tight Binding Approximation ◽  
Quinoid Structure ◽  
Structure Of Carbon Nanotubes

In this paper, we fully describe the geometry of atomic structure of carbon nanotube with quinoid structure. Electronic energy band structure of carbon nanotubes with quinoid structure is studied by tight-binding approximation. In the presence of bond alternation, calculations show that only armchair (n, n) carbon nanotube (without twisting) remains metallic and zigzag (3ν - 1, -3ν + 1) CNT becomes metallic at the critical elongation. Effect of deformation on the change of band gap is also calculated and discussed.

scholarly journals A Review of Electronic Band Structure of Graphene and Carbon Nanotubes Using Tight Binding

2011 ◽  
Vol 2011 ◽  
pp. 1-6 ◽  
Author(s):  
Davood Fathi
Keyword(s):  
Carbon Nanotubes ◽  
Band Structure ◽  
Approximation Theory ◽  
Electronic Band Structure ◽  
Tight Binding ◽  
Single Walled Carbon Nanotubes ◽  
Electronic Band ◽  
Tight Binding Approximation ◽  
Chiral Nanotubes ◽  
Walled Carbon Nanotubes

The electronic band structure variations of single-walled carbon nanotubes (SWCNTs) using Huckle/tight binding approximation theory are studied. According to the chirality indices, the related expressions for energy dispersion variations of these elements are derived and plotted for zigzag and chiral nanotubes.

Electronic band structure of silver low-index surfaces: a tight-binding study

2020 ◽  
Vol 98 (5) ◽  
pp. 488-496
Author(s):  
H.J. Herrera-Suárez ◽  
A. Rubio-Ponce ◽  
D. Olguín
Keyword(s):  
Band Structure ◽  
Density Of States ◽  
Electronic Band Structure ◽  
Local Density ◽  
Tight Binding ◽  
Theoretical Data ◽  
Binding Study ◽  
Local Density Of States ◽  
Electronic Band ◽  
Tight Binding Method

We studied the electronic band structure and corresponding local density of states of low-index fcc Ag surfaces (100), (110), and (111) by using the empirical tight-binding method in the framework of the Surface Green’s Function Matching formalism. The energy values for different surface and resonance states are reported and a comparison with the available experimental and theoretical data is also done.

ADSORPTION OF HYDROGEN AND OXYGEN ON SINGLE AND DOUBLE LAYER STEPPED SI(100) SURFACES

2001 ◽  
Vol 15 (16) ◽  
pp. 2261-2274
Author(s):  
SAED A. SALMAN ◽  
ŞENAY KATIRCIOĞLU ◽  
ŞAKIR ERKOÇ
Keyword(s):  
Band Structure ◽  
Double Layer ◽  
Electronic Band Structure ◽  
Tight Binding ◽  
Electronic Band ◽  
Adsorption Sites ◽  
Initial Stage ◽  
Adsorption Of Hydrogen ◽  
Oxygen Atoms

We have investigated the electronic band structure of hydrogen and oxygen adsorbed single and double layer stepped Si(100) surfaces by Empirical Tight Binding (ETB) method. The total electronic energies of the H,O-SA, DA, DB type stepped Si(100) systems are calculated with limited number of hydrogen and oxygen atoms separately to find out the most probable adsorption sites of the adatoms in the initial stage of hydrogenation and oxidation.

Band Structures of Carbon Nanotubes with Nanoscale Periodic Pores Depending on their Circumferences

2003 ◽  
Vol 02 (01n02) ◽  
pp. 109-116
Author(s):  
Hiroyuki Takeda ◽  
Katsumi Yoshino
Keyword(s):  
Carbon Nanotubes ◽  
Tight Binding ◽  
Band Gaps ◽  
Band Structures ◽  
Electronic Band ◽  
Tight Binding Approximation ◽  
One Dimensional ◽  
Flat Bands ◽  
Porous Graphite ◽  
Electronic Band Structures

We theoretically evaluate the electronic band structures in carbon nanotubes with nanoscale periodic pores with a tight-binding approximation of π electrons, and demonstrate that band gaps of the carbon nanotubes with nanoscale periodic pores differ significantly from those of conventional carbon nanotubes. The band gaps of the carbon nanotubes with nanoscale periodic pores depend strongly on the size of pores and inter-pore distances. In some carbon nanotubes with nanoscale periodic pores, band gaps are constant as a function of their circumferences. In other ones, band gaps have the exact periodicity of three as a function of their circumferences. Those behaviors can be explained by taking properties of nanoscale periodic porous graphite into consideration. In some carbon nanotubes with relatively large nanoscale periodic pores, flat bands appear, which may cause singular properties about magnetism in one-dimensional porous carbon nanotubes.

Tight Binding Modelling of Energy Band Structure in Nitride Heterostructures

2008 ◽  
Vol 8 (2) ◽  
pp. 540-548 ◽  
Author(s):  
Özden Akıncı ◽  
H. Hakan Gürel ◽  
Hilmi Ünlü
Keyword(s):  
Electronic Structure ◽  
Band Structure ◽  
Valence Band ◽  
Nearest Neighbor ◽  
Good Description ◽  
Energy Levels ◽  
Tight Binding ◽  
Binding Theory ◽  
Orbit Splitting ◽  
Atomic Energy Levels

We studied the electronic structure of group III–V nitride ternary/binary heterostructures by using a semi-empirical sp3s* tight binding theory, parametrized to provide accurate description of both valence and conductions bands. It is shown that the sp3s* basis, along with the second nearest neighbor (2NN) interactions, spin-orbit splitting of cation and anion atoms, and nonlinear composition variations of atomic energy levels and bond length of ternary, is sufficient to describe the electronic structure of III–V ternary/binary nitride heterostructures. Comparison with experiment shows that tight binding theory provides good description of band structure of III–V nitride semiconductors. The effect of interface strain on valence band offsets in the conventional Al1−xGaxN/GaN and In1−xGaxN/GaN and dilute GaAs1−xNx/GaAs nitride heterostructures is found to be linear function of composition for the entire composition range (0 ≤ x ≤ 1) because of smaller valence band deformations.

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