In this letter, by use of the first-principles calculations, field emission properties of the body are investigated for a series of dimension-variational single-walled carbon nanotubes (SWNTs). We find that in the course of increasing tube diameter, at low emission currents, field emission properties worsen, chemical stability enhances and binding energy increases, which indicates that optimized field emitter could be achieved; while at high applied voltages, the highest emission current density may appear for the SWNT with some peculiar dimension. We predict that the body of the SWNT could behave as a peculiar field emitter with high threshold voltage and high current density. © 2001 American Institute of Physics.

Zhou Gang;Duan Wenhui;Gu Binglin

Applied Physics Letters

2001

In this article we propose a unified model for ordering and staging of intercalated M ions in the 1T-type intercalation compounds M x TiS 2 . The ordered structures and the stage structures of M ions occupying octahedrally coordinated interstitial sites are studied using the concentration-wave theory. Ten three-dimensional completely ordered structures have been derived by minimizing the eigenvalue of ionic interaction Hamiltonian at high-symmetry points in the first Brillouin zone. An explanation is proposed for several experimental results. © 1999 American Institute of Physics.

Gu Bing-Lin;Song Qing-Gong;Ni Jun

Journal of Applied Physics

1999

Spin tunneling transport properties of two-dimensional electrons through magnetic quantum structures are investigated at zero bias and finite bias. The results indicate that spin-dependent features are not only related with the magnetic configuration, the incident electron energy and the wave-vector, but also closely related with the applied bias. At zero bias, the magnetic quantum structure composed of identical magnetic-barrier and magnetic-well does not show spin-filtering properties, while the magnetic quantum structure composed of unidentical magnetic-barrier and magnetic-well shows distinct spin-filtering properties. Moreover, the applied bias greatly changes electron spin polarization, which makes the former structure also showing interesting spin-dependent features under an applied bias.

Guo Yong;Gu Bing-Lin;Kawazoe Yoshiyuki

Wuli Xuebao Acta Physica Sinica

2000

A special phase transition, the phase transition of ergodic space shrinking in succession (abbreviated as ES³ phase transition), is proposed according to the freezing process of the ordered microregion dipoles in relaxors. Its features are discussed. The special characteristics of relaxors are explained from the viewpoint of the ES³ phase transition. © 1999 Elsevier Science B.V.

Zhang Xiao-Wen;Gui Hong;Liu Zhi-Rong;Gu Bing-Lin

Physics Letters Section A General Atomic and Solid State Physics

1999

By use of the scattering matrix method, we investigate the coupling effects of layers on spin-polarized transport through semimagnetic semiconductor heterostructures with triple paramagnetic layers. Due to the coupling between double non-magnetic layers or among triple paramagnetic layers, spin tunneling exhibits interesting and complex features, which are determined by the structural configuration, the external fields as well as the spin orientations. It is shown that for electrons with either spin orientation tunneling through the symmetric or asymmetric heterostructures with triple paramagnetic layers, transmission resonances can approach the optimum under several biases. Moreover, for asymmetric structures, the resonant enhancement can occur under both several positive and negative biases. The spin-dependent resonant enhancement is also clearly reflected in the current density. In addition, for spin electrons traversing the multilayer heterostructure, the resonant splitting occurs in the transmission, which shows rich variations with the bias. These interesting results may be helpful to the development of spintronic devices.

Zhai F.;Guo Y.;Gu B. L.

European Physical Journal B

2001

We investigate characteristics of spin tunneling time in ZnSe/Ze1-xMnxSe multilayers under the influence of both an electric field and a magnetic field. The results indicate that the tunneling time shows complicated oscillations and significant spin separation for electrons with different spin orientations traversing semimagnetic semiconductor heterostructures. It is also shown that the tunneling time exhibits obvious asymmetry in opposite tunneling directions for electrons tunneling through asymmetric heterostructures, which mainly occurs in resonant regions. The degree of the asymmetry of the tunneling time is not only spin-polarization dependent but also external-field induced.

Guo Y.;Wang B.;Gu B. L.;Kawazoe Y.

European Physical Journal B

2001

We report the energy shifts in an electric field in a Ga1-xAlxAs graded-gap quantum well (GGQW) and a novel method to calculate subbands. Our calculations have revealed the dependence of the energy shifts of subbands and excitons on the field direction in GGQWs. The subband dependence of energy shifts under an electric field in GGQWs is different from that in a square quantum well. © 1989 The American Physical Society.

Zhu Jia-Lin;Gu Bing-Lin;Tang Dao-Hua

Physical Review B

1989

We have investigated transport properties of electrons in magnetic quantum structures under an applied constant electric field. The transmission coefficient and current density have been calculated for electron tunneling through structures consisting of identical magnetic barriers and magnetic wells and structures consisting of unidentical magnetic barriers and magnetic wells. It is shown that the transmission coefficient of electrons in a wider nonresonance energy region is enhanced under an applied electric field. The resonance is suppressed for electron tunneling through double-barrier magnetic(DBM) structures arranged with identical magnetic barriers and magnetic wells. Incomplete resonance at zero bias is changed to complete resonance at proper bias for electron tunneling through DBM structures arranged with different magnetic barriers and magnetic wells. The results also indicate that there exist negative conductivity and noticeable size effect in DBM structures.

Wang Hao;Guo Yong;Gu Bing-Lin

Wuli Xuebao Acta Physica Sinica

1999

Hydrogenated nanocrystalline silicon carbon (nc-SiCx:H) films were prepared by RF glow discharge of gas mixture of silane (SiH4) and ethene (C2H4) diluted heavily by hydrogen (H2). The effect of the gas volume ratio of (SiH4+ C2H4)/H2(Xg) and C2H4/(SiH4+ C2H4) (Xc) on the crystallization and composition of films are described in the paper. When the Xgincreases from 2 to 5%, the volume fraction of the crystalline phase decreases from 48 to 8% and the mean crystallites size is varied from 3.5 to 9 nm because the etching effect of hydrogen becomes weak. When Xg≥ 6%, the deposited films of hydrogenated amorphous silicon carbon are formed. When Xcincreases from 0.1 to 0.4, the volume fraction of the crystalline phase decreases from 45 to 10%, the mean crystallites size decreases from 10 to 5.5 nm, and the C content of the films increases from 0.03 to 0.12. When Xc≥ 0.5, the deposited films are hydrogenated amorphous silicon carbon films. The growth process and crystallization mechanism of nc-SiCx:H films are discussed in detail. Copyright © 1996 Elsevier Science S.A.

Han Weiqiang;Fan Shoushan;Gu Binglin

Materials Science and Engineering B

1996

We adopt the group velocity approach to the issue of tunneling time in two configurations of magnetic barrier structures, which are arranged with identical or unidentical building blocks. The effects of an external electric field are also taken into account. The tunneling time in magnetic barrier structures is found to be strongly dependent on the magnetic configuration, the applied bias, the incident energy as well as the longitudinal wave vector. The results indicate that for electrons with equal energy but different incident angles, the tunneling processes are significantly separated in time within the same magnetic barrier structure. In the configuration arranged with unidentical building blocks, there exists obvious asymmetry of tunneling time in two opposite tunneling directions. Such a discrepancy of the tunneling time varies distinctly with the longitudinal wave vector and the applied bias.

Zhai Feng;Guo Yong;Gu Bing-Lin

European Physical Journal B

2002