Nonanalytical magnetoresistance, the third angular effect, and a methodto investigate Fermi surfaces in quasi-two-dimensional conductors

ABSTRACTTwo optical methods are described for mapping the local variations of refractive index within monoliths of porous silica aerogel. One is an interferometrie measurement that produces “iso-index” fringes in a two dimensional image; an orthogonal view gives the third dimension information. The other method uses the deflection of a He-Ne laser beam to map the gradient index within a sample. The quantification of the measurements is described and the accuracy of the results is discussed.

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CHARGE DENSITY WAVE TRANSITIONS IN TWO-DIMENSIONAL TRANSITION METAL BRONZES AND OXIDES

International Journal of Modern Physics B ◽

10.1142/s0217979293003565 ◽

1993 ◽

Vol 07 (23n24) ◽

pp. 3973-4003 ◽

Cited By ~ 44

Author(s):

P. FOURY ◽

J.P. POUGET

Keyword(s):

Transition Metal ◽

Charge Density ◽

Ground State ◽

Charge Density Wave ◽

Density Wave ◽

Electron Localization ◽

Two Dimensional ◽

Fermi Surfaces ◽

A Charge ◽

Structural Instabilities

The structural instabilities towards the formation of a charge density wave (CDW) ground state exhibited by several layered Mo and W bronzes and oxides are reviewed. It is shown that in these two-dimensional (2D) metals, including the purple bronzes A x Mo 6 O 17 (A=K, Na, Tl; x≈1), the γ and η phases of MO 4 O 11 and the monophosphate tungsten bronzes with pentagonal tunnels ( PO 2)4 ( WO 3)2m(m=4, 6, 7), the CDW instability can be associated with particular chains of MoO 6 or WO 6 octahedra of the ReO 3 type slabs along which there is a strong overlap of the t 2g orbitals. The CDW critical wave vectors of the purple bronzes, Mo 4 O 11 and the tungsten bronzes with m=4 and 6 lead to a common nesting between differently oriented 1D Fermi surfaces. It is suggested that the anharmonic CDW modulation, which occurs in the tungsten bronzes with m≥7, could be the structural fingerprint of electron localization effects.

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THE EFFECT OF THE THIRD DIMENSION ON ROUGH SURFACES FORMED BY SEDIMENTING PARTICLES IN QUASI-TWO-DIMENSIONS

International Journal of Modern Physics B ◽

10.1142/s021797920201004x ◽

2002 ◽

Vol 16 (08) ◽

pp. 1217-1223 ◽

Cited By ~ 1

Author(s):

K. V. MCCLOUD ◽

M. L. KURNAZ

Keyword(s):

Two Dimensions ◽

Scaling Analysis ◽

Silica Spheres ◽

Two Dimensional ◽

One Dimensional ◽

The Third ◽

Roughness Exponent ◽

Third Dimension ◽

Dimensional Cell ◽

Roughness Exponents

The roughness exponent of surfaces obtained by dispersing silica spheres into a quasi-two-dimensional cell is examined. The cell consists of two glass plates separated by a gap, which is comparable in size to the diameter of the beads. Previous work has shown that the quasi-one-dimensional surfaces formed have two roughness exponents in two length scales, which have a crossover length about 1 cm. We have studied the effect of changing the gap between the plates to a limit of about twice the diameter of the beads. If the conventional scaling analysis is performed, the roughness exponent is found to be robust against changes in the gap between the plates; however, the possibility that scaling does not hold should be taken seriously.

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Laminar flow in symmetrical channels with slightly curved walls II. An asymptotic series for the stream function

Proceedings of the Royal Society of London Series A - Mathematical and Physical Sciences ◽

10.1098/rspa.1963.0061 ◽

1963 ◽

Vol 272 (1350) ◽

pp. 406-428 ◽

Cited By ~ 28

Keyword(s):

Laminar Flow ◽

Asymptotic Series ◽

Radius Of Curvature ◽

Two Dimensional ◽

The Third ◽

Higher Order Terms ◽

Curvature Parameter ◽

Leading Term ◽

Flow Through ◽

Curved Walls

A class of two-dimensional channels, with walls whose radius of curvature is uniformly large relative to local channel width, is described, and the velocity field of laminar flow through these channels is obtained as a power series in the small curvature parameter. The leading term is the Jeffery-Hamel solution considered in part I, and it is shown here how the higher-order terms are found. Terms of the third approximation have been computed. The theory is applied to two examples, for one of which experimental results are available and confirm the theoretical values with fair accuracy.

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Dispersion relations of dust lattice waves in two-dimensional honeycomb configuration

Journal of Plasma Physics ◽

10.1017/s0022377813000123 ◽

2013 ◽

Vol 79 (5) ◽

pp. 629-633

Author(s):

B. FAROKHI

Keyword(s):

Dispersion Relation ◽

Group Velocity ◽

Hexagonal Lattice ◽

Dispersion Relations ◽

Two Dimensional ◽

The Third ◽

Lattice Waves ◽

The Waves

AbstractThe linear dust lattice waves propagating in a two-dimensional honeycomb configuration is investigated. The interaction between particles is considered up to distance 2a, i.e. the third-neighbor interactions. Longitudinal and transverse (in-plane) dispersion relations are derived for waves in arbitrary directions. The study of dispersion relations with more neighbor interactions shows that in some cases the results change physically. Also, the dispersion relation in the different direction displays anisotropy of the group velocity in the lattice. The results are compared with dispersion relations of the waves in the hexagonal lattice.

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R-Process Nucleosynthesis in MHD Jet Explosions of Core-Collapse Supernovae

Journal of Astrophysics ◽

10.1155/2013/506146 ◽

2013 ◽

Vol 2013 ◽

pp. 1-13

Author(s):

Motoaki Saruwatari ◽

Masa-aki Hashimoto ◽

Ryohei Fukuda ◽

Shin-ichiro Fujimoto

Keyword(s):

Magnetic Field ◽

Heavy Element ◽

Initial Conditions ◽

Core Collapse ◽

Combined Effects ◽

Two Dimensional ◽

The Third ◽

R Process ◽

Helium Star ◽

Hydrodynamic Code

We investigate the r-process nucleosynthesis during the magnetohydrodynamical (MHD) explosion of a supernova in a helium star of 3.3 M⊙, where effects of neutrinos are taken into account using the leakage scheme in the two-dimensional (2D) hydrodynamic code. Jet-like explosion due to the combined effects of differential rotation and magnetic field is able to erode the lower electron fraction matter from the inner layers. We find that the ejected material of low electron fraction responsible for the r-process comes out from just outside the neutrino sphere deep inside the Fe-core. It is found that heavy element nucleosynthesis depends on the initial conditions of rotational and magnetic fields. In particular, the third peak of the distribution is significantly overproduced relative to the solar system abundances, which would indicate a possible r-process site owing to MHD jets in supernovae.

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