Influence Of Transverse Electric Field Research Articles

Dramatic effect of a transverse electric field on frictional properties of graphene

I study the influence of transverse electric fields on the interfacial forces between a graphene layer and a carbon nanotube tip by means of atomistic simulations, in which a Gaussian regularized charge-dipole potential is combined with classical force fields. A significant effect of the field-induced electric charge on the normal force is observed. The normal pressure is found to be sensitive to the presence of a transverse electric field, while the friction force remains relatively invariant for the here-used field intensities. The contact can even be turned to have a negative coefficient of friction in a constant-distance scenario when the field strength reaches a critical value, which increases with decreasing tip-surface distance. These results shed light on how the frictional properties of nanomaterials can be controlled via applied electric fields.

Electrically controlled quantum spin Hall in narrow zigzag graphene nanoribbon

Using the tight binding Kane-Mele model including the self-consistent on-site Coulomb interactions (O-CIs), we study the influence of transverse electric field in the narrow zigzag graphene nanoribbon (ZGNR) plane on the edge band structure in order to investigate the way to control the type of quantum spin Hall (QSH) system in the ZGNR. The theoretical results show that when applying weak electric field intensity, the direction of electric field can adjust these two spin-down edge bands moving along the different directions in one-dimensional q space, which leads to the two different types of degenerative breakdown of two pure spin-down edge states at q=0.5. When applying positive electric field the energy of spin-down edge band at edge site 1 is higher than that at edge site 8. On the contrary, when applying negative electric field the energy of spin-down edge band at edge site 8 is higher than that at edge site 1. It shows that we can use the direction of electric field to control the two spin-down edge currents occurring at two different energies. Further, when the electric field intensity increases above 0.69 V/nm, the increased large band gap between the two spin-down edge bands leads to the inversion of these two spin-down edge bands. That is to say, there is a spin-down band gap, however, there is not a band gap for spin-up edge band in the region of spin-down band gap. Thus the system becomes half-metallic, and the QSH does not belong in the type B any longer. Specially, when the electric field intensity reaches 1.17 V/nm in the region of spin-down band gap, the pure spin-up edge state appears at q=0.5, which shows that the strong pure spin-up edge current along the edge site 8 can occur. With increasing the intensity of electric field, the QSH system undergoes three processes from the type B to the type C. When the electric field intensity is more than 1.42 V/nm, the two spin-up edge bands also present band inversion and turn into the conduction band and the valence band, respectively. Thus the system becomes semiconducting and the QSH system does not belong in the type C, ordinary quantum Hall system. Finally, according to the results discussed above, we can expect that using the direction and the intensity of the transverse electric field in plane we can adjust the properties of edge current, and control the type of QSH system varying from the type B to the type C.

Influence of Transverse Electric Field on Dielectric Permittivity of Triglycine Sulfate

Dielectric permittivity along the b-axis of triglycine sulfate under and after application of an electric field has been examined at various temperatures. Both relaxation behaviour of the permittivity under the application and that after discontinuance of the application are different between the transverse electric field and the longitudinal one. Temperature dependences of the permittivity prove that the memory effect which indicates the temperature where the electric field has been applied is easily observed after application of the transverse electric field.

Observation of the Giant Stark Effect in Boron-Nitride Nanotubes

Bias dependent scanning tunneling microscopy and scanning tunneling spectroscopy have been used to characterize the influence of transverse electric fields on the electronic properties of boron-nitride nanotubes (BNNTs). We find experimental evidence for the theoretically predicted giant Stark effect. The observed giant Stark effect significantly reduces the band gap of BNNTs and thus greatly enhances the utility of BNNTs for nanoscale electronic, electromechanical, and optoelectronic applications.

Influence of transverse electric field on the photoluminescence linewidth of excitonic transition in quantum wells: Alloy disorder and composition fluctuation contributions

The influence of transverse electric field on the photoluminescence linewidth of excitonic transition in a semiconductor quantum well structure is examined within a theoretical model which ascribes the origin of the linewidth to band-edge discontinuity fluctuations arising from local compositional fluctuations at the interfaces, and to short-ranged alloy disorder scattering. In particular, the model is applied to the AlxGa1−xAs/GaAs system and the dependence of linewidth on the width of the quantum well, the average composition of the alloy, the amplitude of composition fluctuation, and the value of applied field (0–100 kV/cm) is studied.