89 research outputs found
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 -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
- …