جستجوی مقالات مرتبط با کلیدواژه « electronic conductance » در نشریات گروه « فیزیک »

In this paper, we study the electronic conductance of a nanoribbon with square lattice by using Green’s function theory within the tight-binding approach. For this purpose, we separate the conductance modes in the ideal parts by using a suitable unitary transformation in order to obtain the analytic formula for the corresponding self-energies. Then, we present a fast computer algorithm based on the Fisher-Lee formula for the calculation of the system conductance. The results show that the distribution of electrical impurities with different on-site energies leads to the different values of the system electronic conductance and it is generally decreasing.

In this paper, the electronic transport of a graphene nanoribbon including a bond defect as well as a polyacetylene nanowire, including an extra bond, has been studied based on Green's function technique at the tight-binding approach. The results show that the behavior of electronic conductance is different in resonance and nonresonance cases with respect to variation of bond defect position. The conductance value at the zero energy tunes by variation of defect position, only for the cases which includes double bonds. These changes is more observable especially at the polyacetylene nanowires. The amount of antiresonance shift with respect to bond defect position, in conductance spectrum, strongly depends on type and shape of center wire structure.

In this paper, we study the electronic conductance of a simple chain -as well as a polyacetylene oligomer- which is connected to three one-dimensional metallic leads. The calculations are based on Green’s function technique within the nearest neighbor tight-binding approach. Two types of conductances, one which is measured between left and right leads and another which is measured between left and top leads, are calculated as functions of energy; and their behaviors are investigated with respect to the position of the top lead connection in the center wire. The results show that the existence and the position of third lead in the center wire strongly effects on the values and behaviors of the mentioned electronic conductances. For polyacetylene case, the value of each conductance at zero energy can be tuned by variation of third lead position.

In this paper, we studied the electronic conductance of a carbon nanoring using Green’s function method at the tight-binding approach for different positions of contacts in the presence and absence of magnetic field. The results show that as the conductors approch in the nanoring, the tunneling conductance in the gap region improves. Moreover, applying the magnetic field dramatically influences the conductance spectrum of the nanoring so that the existence of the magnetic field causes the configurations with coinciding conductance to be disarticulated. The study of the carbon nanoring including binary benzene rings indicates that the variation of the position of these benzene rings in the nanoring shifts the positions of anti-resonances in the conductance spectrum.

In this paper, the electronic conductance of a polyacetylene polymer embedded between two simple chains is studied by using transfer matrix method within the tight-binding and first neighbor approach. Also, by adding benzene molecules to polyacetylene we obtain the system conductance in its conversion to polystyrene polymer. The results show that as the number of benzene molecules in the middle of center system increases the conductance in the tunneling area of polyacetylene improves and this area comes close to the resonance area. In contrast, a part of resonance area tends to transform into polystyrene tunneling zone.

The present research studied the electronic transport of an ideal infinite ladder nanostructure in the presence/absence of network defects by using Green’s function method at the tight-binding approximation. The network defects can be simulated by considering a finite ladder which is connected via two contacts to two similar infinite ladders. The results showed that the hopping energy of rungs determines the overlapping region of the ladder conductance channels. By increasing hopping energy of rungs, the allowed energy region of the ladder increases, while the overlapping region shrinks and eventually vanishes. Creation of branched bonds in the center ladder leads, through the system, to a harder electron tunneling. Moreover, the closer electron energy to the system gap edges leads to a better tunneling.