SPIN-ORBIT COUPLING IN GRAPHENE UNDER UNIAXIAL STRAIN: TIGHT-BINDING APPROACH AND FIRST-PRINCIPLES CALCULATIONS

2011 ◽  
Vol 25 (11) ◽  
pp. 823-830 ◽  
Author(s):  
BAIHUA GONG ◽  
XIN-HUI ZHANG ◽  
ER-HU ZHANG ◽  
SHENG-LI ZHANG
Keyword(s):  
Band Gap ◽  
First Principles ◽  
Tight Binding ◽  
Uniaxial Strain ◽  
Orbit Coupling ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
First Principles Calculations ◽  
Binding Model ◽  
Tight Binding Approximation

Tuning the spin-orbit coupling (SOC) in graphene is highly desired for its application in spintronics. In this paper, we calculated the band gap induced by SOC in graphene under uniaxial strain from a tight-binding model, and found that the band gap has a monotonic increasing dependence on the strain in the range of -20% to 15%. Our results suggest that strain can be used as a reversible and controllable way to tune the SOC in graphene. First-principles calculations were performed, confirming the results of tight-binding approximation.

scholarly journals Intrinsic Spin-Orbit Coupling in Zigzag and Armchair Graphene Nanoribbons

2011 ◽  
Vol 2011 ◽  
pp. 1-7
Author(s):  
Ying Li ◽  
Erhu Zhang ◽  
Baihua Gong ◽  
Shengli Zhang
Keyword(s):  
Graphene Nanoribbons ◽  
Tight Binding ◽  
Geometrical Parameters ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Binding Model ◽  
Tight Binding Approximation ◽  
Energy Gaps ◽  
Armchair Graphene Nanoribbons ◽  
Armchair Graphene

Starting from a tight-binding model, we derive the energy gaps induced by intrinsic spin-orbit (ISO) coupling in the low-energy band structures of graphene nanoribbons. The armchair graphene nanoribbons may be either semiconducting or metallic, depending on their widths in the absence of ISO interactions. For the metallic ones, the gaps induced by ISO coupling decrease with increasing ribbon widths. For the ISO interactions, we find that zigzag graphene nanoribbons with odd chains still have no band gaps while those with even chains have gaps with a monotonic decreasing dependence on the widths. First-principles calculations have also been carried out, verifying the results of the tight-binding approximation. Our paper reveals that the ISO interaction of graphene nanoribbons is governed by their geometrical parameters.

Quantum anomalous Hall effect on a square lattice with spin–orbit couplings and an exchange field

2014 ◽  
Vol 92 (5) ◽  
pp. 420-424 ◽  
Author(s):  
Xiaoyong Guo ◽  
Xiaobin Ren ◽  
Guangjie Guo ◽  
Jie Peng
Keyword(s):  
Tight Binding ◽  
Chern Number ◽  
Orbit Coupling ◽  
Square Lattice ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Exchange Field ◽  
Edge States ◽  
Binding Model ◽  
Spatial Direction

We investigate a tight-binding model on a two-dimensional square lattice with three terms: the Rashba spin–orbit coupling, the real amplitude next-nearest spin–orbit coupling, and an exchange field. We calculate the first Chern number to identify band topology. It is found that the Chern number takes the quantized values of C1 = 1, 2 and the chiral edge modes can be obtained. Therefore our model realizes the quantum anomalous Hall (QAH) effect. The Rashba coupling is positive for the QAH phase while the next-nearest coupling is detrimental to it. By increasing the exchange field intensity, the Chern number changes from quantized value 2 to 0. The behavior of the edge states is also studied. Particularly for C1 = 2 case, there are two gapless spin-polarized edge states with the same spin polarization moving in the same spatial direction. This indicates that their appearance is topological rather than accidental.

Thermoelectric properties of half-Heusler ZrNiPb by using first principles calculations

RSC Advances ◽  
2016 ◽  
Vol 6 (53) ◽  
pp. 47953-47958 ◽  
Author(s):  
San-Dong Guo
Keyword(s):  
Thermoelectric Properties ◽  
First Principles ◽  
Electronic Structures ◽  
Orbit Coupling ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
First Principles Calculations ◽  
Generalized Gradient ◽  
Generalized Gradient Approximation

We investigate the electronic structures and thermoelectric properties of a recently synthesized half-Heusler ZrNiPb compound by using a generalized gradient approximation (GGA) and GGA plus spin–orbit coupling (GGA + SOC).

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