Competition between magnetic field dependent band structure and coherent backscattering in multiwall carbon nanotubes

Magnetotransport measurements in large diameter multiwall carbon nanotubes (20-40 nm) demonstrate the competition of a magnetic-field dependent bandstructure and Altshuler-Aronov-Spivak oscillations. By means of an efficient capacitive coupling to a backgate electrode, the magnetoconductance oscillations are explored as a function of Fermi level shift. Changing the magnetic field orientation with respect to the tube axis and by ensemble averaging, allows to identify the contributions of different Aharonov-Bohm phases. The results are in qualitative agreement with numerical calculations of the band structure and the conductance.Comment: 4 figures, 5 page

Spectral and Diffusive Properties of Silver-Mean Quasicrystals in 1,2, and 3 Dimensions

Spectral properties and anomalous diffusion in the silver-mean (octonacci) quasicrystals in d=1,2,3 are investigated using numerical simulations of the return probability C(t) and the width of the wave packet w(t) for various values of the hopping strength v. In all dimensions we find C(t)\sim t^{-\delta}, with results suggesting a crossover from \delta<1 to \delta=1 when v is varied in d=2,3, which is compatible with the change of the spectral measure from singular continuous to absolute continuous; and we find w(t)\sim t^{\beta} with 0<\beta(v)<1 corresponding to anomalous diffusion. Results strongly suggest that \beta(v) is independent of d. The scaling of the inverse participation ratio suggests that states remain delocalized even for very small hopping amplitude v. A study of the dynamics of initially localized wavepackets in large three-dimensional quasiperiodic structures furthermore reveals that wavepackets composed of eigenstates from an interval around the band edge diffuse faster than those composed of eigenstates from an interval of the band-center states: while the former diffuse anomalously, the latter appear to diffuse slower than any power law.Comment: 11 pages, 10 figures, 1 tabl

Boron and nitrogen codoping effect on transport properties of carbon nanotubes

International audienceThis paper reports a theoretical study of the effect of boron and nitrogen codoping on the transport properties of carbon nanotubes (CNTs) at the mesoscopic scale. A new tight-binding parametrization has been set up, based on density functional theory calculations, that enables a reliable description of the electronic structure of realistic BN-doped CNTs. With this model, we have carried out a deep analysis of the electronic mean free path (MFP) exhibited by these nanostructures. The MFP is highly sensitive to the geometry of the scattering centers. We report that the relative distance between B and N atoms in the network influences drastically the electronic conduction. Moreover, we point out that the scattering induced by small hexagonal BN domains in the carbon network is less important than the BN-pair case

Le séro A. B. R. et l’épreuve du “ Culot ” dans le diagnostic des brucelloses animales et humaines

Rossi Paul, Triozon F., Goguillot Th. Le séro A.B.R. et l'épreuve du «Culot» dans le diagnostic des brucelloses animales et humaines. In: Bulletin de l'Académie Vétérinaire de France tome 107 n°8, 1954. pp. 475-478

L’épreuve de Vanneau (Abortus-Bang-Ringprobe ou Ring-Test) avec les laits chauffés

Rossi Paul, Triozon F., Dutilloy Y., Goguillot Th. L’épreuve de l’anneau (Abortus-Bang-Ringprobe ou Ring-Test) avec les laits chauffés. In: Bulletin de l'Académie Vétérinaire de France tome 107 n°8, 1954. pp. 419-422

La réaction du « culot » ou « Kuppenreaktion » dans le diagnostic de la Brucellose bovine

Rossi P., Triozon F., Dutilloy Y., Goguillot Th. La réaction du «Culot » ou» Kuppenreaktion» dans le diagnostic de la Brucellose bovine. In: Bulletin de l'Académie Vétérinaire de France tome 107 n°4, 1954. pp. 179-182

Le séro-A.B.R. et l’épreuve du « Culot » (Kuppenreaktion) dans le diagnostic des Brucelloses, bovine et équine

Rossi P., Triozon F., Dutilloy Y., Goguillot Th. Le séro A.B.R. et l’épreuve du «Culot » (Kuppenreaktion) dans le diagnostic des Brucelloses, bovine et équine. In: Bulletin de l'Académie Vétérinaire de France tome 107 n°5, 1954. pp. 269-275

Quantum Transport Length Scales in Silicon-based Semiconducting Nanowires: Surface Roughness Effects

We report on a theoretical study of quantum charge transport in atomistic models of silicon nanowires with surface roughness-based disorder. Depending on the nanowires features (length, roughness profile) various conduction regimes are explored numerically by using efficient real space order N computational approaches of both Kubo-Greenwood and Landauer-Buttiker transport frameworks. Quantitative estimations of the elastic mean free paths, charge mobilities and localization lengths are performed as a function of the correlation length of the surface roughness disorder. The obtained values for charge mobilities well compare with the experimental estimates of the most performant undoped nanowires. Further the limitations of the Thouless relationship between the mean free path and the localization length are outlined.Comment: 13 pages, to appear in PR

Generalized quasiperiodic Rauzy tilings

We present a geometrical description of new canonical $d$-dimensional codimension one quasiperiodic tilings based on generalized Fibonacci sequences. These tilings are made up of rhombi in 2d and rhombohedra in 3d as the usual Penrose and icosahedral tilings. Thanks to a natural indexing of the sites according to their local environment, we easily write down, for any approximant, the sites coordinates, the connectivity matrix and we compute the structure factor.Comment: 11 pages, 3 EPS figures, final version with minor change