Spin polarization current induced by hydrogen hybrid within closed hexagon graphene nanoribbon devices

2016 ◽  
Vol 30 (27) ◽  
pp. 1650333 ◽  
Author(s):  
Yun Ren ◽  
Jun He ◽  
Zhi-Qiang Fan ◽  
Xiang Zhu ◽  
Yi Liu ◽  
...  
Keyword(s):  
Density Functional ◽  
Differential Resistance ◽  
Graphene Nanoribbon ◽  
Polarization Current ◽  
Functional Theory ◽  
Molecular Switching ◽  
The Density Functional Theory ◽  
Spin Polarized ◽  
Negative Differential Resistance Effect ◽  
Filtering Effect

We investigate the spin-polarized electronic transport properties of the closed hexagon graphene nanoribbon devices with different hydrogen hybrid of edge carbon atoms by using non-equilibrium Green’s functions in combination with the density functional theory. The results show that an excellent molecular switching with on/off ratio over 106, perfect spin-filtering effect and negative differential resistance effect have been observed. A detailed analysis has been presented.

Gate-modulated electronic transport through a graphene nanoribbon composed of nanoribbons of different widths

2015 ◽  
Vol 14 (01) ◽  
pp. 1550005 ◽  
Author(s):  
Wen Liu ◽  
Jie Cheng ◽  
Jian-Hua Zhao ◽  
Cai-Juan Xia ◽  
De-Sheng Liu
Keyword(s):  
Integrated Circuits ◽  
Electronic Transport ◽  
Density Functional ◽  
Differential Resistance ◽  
Graphene Nanoribbon ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Effective Transport ◽  
Transport Channels ◽  
Non Equilibrium Green’S Function

Based on the non-equilibrium Green's function (NEGF) method combined with the density functional theory (DFT), we have studied the gate-modulated electronic properties of a graphene nanoribbon (GNR) which is composed of two GNRs of different widths. The results show that the charge transport is greatly modulated by the applied gate. Negative differential resistance (NDR) behaviors is found in such a system. With the increase in the gate, the NDR behaviors will disappear and reappear. Furthermore, under certain gate voltages multiple NDR behavior is found, the origin of which is attributed to the change of the number of effective transport channels and the variation of delocalization degree of the orbitals within the bias window. Interestingly, low bias NDR behavior is obtained which is desirable for integrated circuits from the point view of power consumption.

A molecular device providing a remarkable spin filtering effect due to the central molecular stretch caused by lateral zigzag graphene nanoribbon electrodes

2020 ◽  
Vol 22 (12) ◽  
pp. 6755-6762 ◽  
Author(s):  
Xiaoyue Liu ◽  
Jueming Yang ◽  
Xingwu Zhai ◽  
Hongxia Yan ◽  
Yanwen Zhang ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Graphene Nanoribbon ◽  
Molecular Devices ◽  
Molecular Device ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Filtering Effect ◽  
Spin Filtering

Through the density functional theory, we studied molecular devices composed of single tetrathiafulvalene (TTF) molecules connected with zigzag graphene nanoribbon electrodes by four different junctions.

scholarly journals A NOVEL FRACTAL GEOMETRY DOPING FOR GRAPHENE NANORIBBON AND THE OPTIMIZATION OF CRYSTAL: A DENSITY FUNCTIONAL THEORY (DFT) STUDY

2020 ◽  
Vol 17 (35) ◽  
pp. 1148-1158
Author(s):  
Mohammed L. JABBAR ◽  
Kadhum J. AL-SHEJAIRY
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Energy Gap ◽  
Minimum Energy ◽  
Graphene Nanoribbon ◽  
Chemical Doping ◽  
Functional Theory ◽  
Lower Reactivity ◽  
The Density Functional Theory ◽  
Semiconductor Behavior

Chemical doping is a promising route to engineering and controlling the electronic properties of the zigzag graphene nanoribbon (ZGNR). By using the first-principles of the density functional theory (DFT) calculations at the B3LYP/ 6-31G, which implemented in the Gaussian 09 software, various properties, such as the geometrical structure, DOS, HOMO, LUMO infrared spectra, and energy gap of the ZGNR, were investigated with various sites and concentrations of the phosphorus (P). It was observed that the ZGNR could be converted from linear to fractal dimension by using phosphorus (P) impurities. Also, the fractal binary tree of the ZGNR and P-ZGNR structures is a highlight. The results demonstrated that the energy gap has different values, which located at this range from 0.51eV to 1.158 eV for pristine ZGNR and P-ZGNR structures. This range of energy gap is variable according to the use of GNRs in any apparatus. Then, the P-ZGNR has semiconductor behavior. Moreover, there are no imaginary wavenumbers on the evaluated vibrational spectrum confirms that the model corresponds to minimum energy. Then, these results make P-ZGNR can be utilized in various applications due to this structure became more stable and lower reactivity.

scholarly journals Quantum transport in zigzag graphene nanoribbon decorated with a phenanthrene molecule

2021 ◽  
Author(s):  
Bo Jiang ◽  
Qing-Yuan Chen ◽  
Jinlong Luo ◽  
Yifen Zhao ◽  
GuoJun Jin ◽  
...  
Keyword(s):  
Quantum Transport ◽  
Density Functional ◽  
Physical Mechanism ◽  
Differential Resistance ◽  
Graphene Nanoribbon ◽  
Hybrid Structures ◽  
Differential Conductance ◽  
First Principles Calculations ◽  
Functional Theory ◽  
Carbon Chains

Abstract By using the first principles calculations which combine density functional theory and nonequilibrium Green's function, we investigate the nanoscopic quantum transport of three hybrid structures consisting of a phenanthrene (PHE) molecule and a zigzag graphene nanoribbon (ZGNR). It is found that after decorated with the PHE molecule, the ZGNRs with the odd (even) zigzag carbon chains show the conductance reduction (enhancement), respectively. With the increase of the number of carbon chains, this odd-even difference will disappear. Moreover, negative differential resistance behavior can also be found in the hybrid structures consisting of the PHE molecule and the antisymmetric ZGNR. Finally, the differential conductance, transmission spectra, and molecular projection self-consistent Hamiltonian are used to explain the physical mechanism clearly. Accordingly, the proposed structures could have broad applications in the design of molecular nanodevices.

FERROMAGNETIC PROPERTIES IN V-DOPED AlN FROM FIRST PRINCIPLES

2012 ◽  
Vol 26 (20) ◽  
pp. 1250132
Author(s):  
G. Y. YAO ◽  
G. H. FAN ◽  
J. H. MA ◽  
S. W. ZHENG ◽  
J. CHEN ◽  
...  
Keyword(s):  
First Principles ◽  
Density Functional ◽  
Room Temperature ◽  
Magnetic Semiconductor ◽  
Double Exchange ◽  
Functional Theory ◽  
Zinc Blende ◽  
The Density Functional Theory ◽  
Spin Polarized ◽  
Ferromagnetic Ground State

Using the first-principles method based on the density functional theory, we have calculated electronic structure of zinc blende AlN doped with 6.25% of V. The V dopants are found spin polarized and the calculated band structures suggest a 100% polarization of the conduction carriers. The ferromagnetic ground state in V-doped AlN can be explained in terms of double-exchange mechanism, and a Curie temperature above room temperature can be expected. These results suggest that the V-doped AlN may present a promising dilute magnetic semiconductor and find applications in the field of spintronics.

Modulation of Low Bias Negative Differential Resistance in a Molecular Device by Adjusting Anchoring Groups

2014 ◽  
Vol 1070-1072 ◽  
pp. 479-482
Author(s):  
Li Hua Wang ◽  
Heng Fang Meng ◽  
Bing Jun Ding ◽  
Yong Guo
Keyword(s):  
Electronic Transport ◽  
Negative Differential Resistance ◽  
Density Functional ◽  
Function Method ◽  
Differential Resistance ◽  
Carbon Chain ◽  
Molecular Device ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Anchoring Groups

We investigate electronic transport properties of molecular device models constructed by a dipyrimidinyl–dimethyl molecule embedding in a carbon chain, which are then coupled to the gold electrodes through thiol or isocyanide group. Using the density functional theory combined with the nonequilibrium Green’s function method, negative differential resistance behaviors are observed in such molecular junctions. Most importantly, system with the isocyanide group can achieve a larger negative differential resistance at lower bias voltage (0.1V).

An ab initio study on the transport characteristics of Si2C2 clusters

2020 ◽  
Vol 98 (1) ◽  
pp. 11-15 ◽  
Author(s):  
Wei Hu ◽  
Qinglin Wang ◽  
Qinghua Zhou ◽  
Wenhua Liu ◽  
Yan Liang ◽  
...  
Keyword(s):  
Transport Properties ◽  
Density Functional ◽  
Central Area ◽  
Differential Resistance ◽  
Switching Behavior ◽  
Contact Structures ◽  
Functional Theory ◽  
Molecular Switching ◽  
Resonant Transmission ◽  
Non Equilibrium Green’S Function

We have studied the transport properties of three different contact structures in Si2C2 clusters by using the first principles based on density functional theory (DFT) and non-equilibrium Green’s function (NEGF) in this paper. Both M1 and M2 show excellent transport properties and a weak negative differential resistance (NDR) phenomenon appears due to greater transferring charge between the central area and the electrodes. The intermediate barrier of M3 is very large, and the electrons are difficult to transmit. However, it also shows good conductivity after we add sulfur (S) atoms at both ends of the molecule. Through the molecular projected self-consistent Hamiltonian (MPSH) analysis, the molecular orbital is expanded with the addition of S atoms, thus showing good conductivity. With the addition of the bias, the conductance of Si2C2 clusters at the Fermi level is reduced due to the drift of the energy level. It is interesting to note that there is a high resonant transmission peak at −1.14 eV under 2 V bias of the M3 system, which shows a molecular switching behavior.

A Density Functional Theory Study of Gd8O12 Cluster

2012 ◽  
Vol 542-543 ◽  
pp. 1418-1421
Author(s):  
Qing Xiang Gao ◽  
Lin Xu ◽  
Bo Wu
Keyword(s):  
Density Functional Theory ◽  
Magnetic Properties ◽  
Density Functional ◽  
Magnetic Moments ◽  
Generalized Gradient ◽  
Cage Structure ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Spin Polarized ◽  
Ionic Bonds

The spin-polarized generalized gradient approximation to the density functional theory is used to determine the geometries, stability, electronic structures, and magnetic properties of the Gd8O12cluster. Our work reveals that the ground state configuration of the Gd8O12cluster is a hexahedral cage structure with Cisymmetry. The electronic and magnetic properties imply that the formations of the ionic bonds between the adjacent Gd and O atoms result in the high stability of the Gd8O12cluster, which is due to the charge transfers between the Gd 5d, 6s electrons to O 2p orbital. It is also confirmed by the electron densities of HOMO-LUMO states. In addition, the analysis of the magnetic properties implies the total magnetic moments are mostly dominated by the Gd 4f orbital.

Spin transport properties in lower n-acene–graphene nanojunctions

2015 ◽  
Vol 17 (17) ◽  
pp. 11292-11300 ◽  
Author(s):  
Dongqing Zou ◽  
Bin Cui ◽  
Xiangru Kong ◽  
Wenkai Zhao ◽  
Jingfen Zhao ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Transport Properties ◽  
Density Functional ◽  
Spin Transport ◽  
Graphene Nanoribbon ◽  
Function Technique ◽  
Functional Theory ◽  
Spin Polarized ◽  
Non Equilibrium Green’S Function ◽  
Non Equilibrium

A series of n-acene–graphene (n = 3, 4, 5, 6) devices, in which n-acene molecules are sandwiched between two zigzag graphene nanoribbon (ZGNR) electrodes, are modeled through the spin polarized density functional theory combined with the non-equilibrium Green's function technique.

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