1,280 research outputs found
Weak topological insulator with protected gapless helical states
A workable model for describing dislocation lines introduced into a
three-dimensional topological insulator is proposed. We show how fragile
surface Dirac cones of a weak topological insulator evolve into protected
gapless helical modes confined to the vicinity of dislocation line. It is
demonstrated that surface Dirac cones of a topological insulator (either strong
or weak) acquire a finite-size energy gap, when the surface is deformed into a
cylinder penetrating the otherwise surface-less system. We show that when a
dislocation with a non-trivial Burgers vector is introduced, the finite-size
energy gap play the role of stabilizing the one-dimensional gapless states.Comment: 8 pages, 17 figure
Solvent Extraction of V(III, IV, V) with Acetylacetone
開始ページ、終了ページ: 冊子体のページ付
Zigzag edge modes in Z2 topological insulator: reentrance and completely flat spectrum
The spectrum and wave function of helical edge modes in Z_2 topological
insulator are derived on a square lattice using Bernevig-Hughes-Zhang (BHZ)
model. The BHZ model is characterized by a "mass" term M (k) that is
parameterized as M (k) = Delta - B k^2. A topological insulator realizes when
the parameters Delta and B fall on the regime, either 0 < Delta /B < 4 or 4 <
Delta /B < 8. At Delta /B = 4, which separates the cases of positive and
negative (quantized) spin Hall conductivities, the edge modes show a
corresponding change that depends on the edge geometry. In the (1,0)-edge, the
spectrum of edge mode remains the same against change of Delta /B, although the
main location of the mode moves from the zone center for Delta /B < 4, to the
zone boundary for Delta /B > 4 of the 1D Brillouin zone. In the (1,1)-edge
geometry, the group velocity at the zone center changes sign at Delta /B = 4
where the spectrum becomes independent of the momentum, i.e. flat, over the
whole 1D Brillouin zone. Furthermore, for Delta/B < 1.354..., the edge mode
starting from the zone center vanishes in an intermediate region of the 1D
Brillouin zone, but reenters near the zone boundary, where the energy of the
edge mode is marginally below the lowest bulk excitations. On the other hand,
the behavior of reentrant mode in real space is indistinguishable from an
ordinary edge mode.Comment: 19 pages, 33 figure
Synergic Extraction of Rare Earth Elements with Thenoyltrifluoroacetone and Neutral Bidentate Ligands
開始ページ、終了ページ: 冊子体のページ付
Substoichiometric Isotope Dilution Analysis of Vanadium by Synergistic Extraction
開始ページ、終了ページ: 冊子体のページ付
Tunneling into fractional quantum Hall liquids
Motivated by the recent experiment by Grayson et.al., we investigate a
non-ohmic current-voltage characteristics for the tunneling into fractional
quantum Hall liquids. We give a possible explanation for the experiment in
terms of the chiral Tomonaga-Luttinger liquid theory. We study the interaction
between the charge and neutral modes, and found that the leading order
correction to the exponent is of the order of
, which reduces the exponent . We
suggest that it could explain the systematic discrepancy between the observed
exponents and the exact dependence.Comment: Latex, 5 page
Solvent Extraction of Lanthanoid(III) with 18-Crown-6 and Trichloroacetate Ion
開始ページ、終了ページ: 冊子体のページ付
Spin Berry phase in the Fermi arc states
Unusual electronic property of a Weyl semi-metallic nanowire is revealed. Its
band dispersion exhibits multiple subbands of partially flat dispersion,
originating from the Fermi arc states. Remarkably, the lowest energy flat
subbands bear a finite size energy gap, implying that electrons in the Fermi
arc surface states are susceptible of the spin Berry phase. This is shown to be
a consequence of spin-to-surface locking in the surface electronic states. We
verify this behavior and the existence of spin Berry phase in the low-energy
effective theory of Fermi arc surface states on a cylindrical nanowire by
deriving the latter from a bulk Weyl Hamiltonian. We point out that in any
surface state exhibiting a spin Berry phase pi, a zero-energy bound state is
formed along a magnetic flux tube of strength, hc/(2e). This effect is
highlighted in a surfaceless bulk system pierced by a dislocation line, which
shows a 1D chiral mode along the dislocation line.Comment: 9 pages, 9 figure
Anomalous tunneling conductances of a spin singlet \nu=2/3 edge states: Interplay of Zeeman splitting and Long Range Coulomb Interaction
The point contact tunneling conductance between edges of the spin singlet
quantum Hall states is studied both in the
quasiparticle tunneling picture and in the electron tunneling picture. Due to
the interplay of Zeeman splitting and the long range Coulomb interaction
between edges of opposite chirality novel spin excitations emerge, and their
effect is characterized by anomalous exponents of the charge and spin tunneling
conductances in various temperature ranges. Depending on the kinds of
scatterings at the point contact and the tunneling mechanism the anomalous
interaction in spin sector may enhance or suppress the tunneling conductances.
The effects of novel spin excitation are also relevant to the recent NMR
experiments on quantum Hall edges.Comment: Revtex File, 7 pages: To be published in Physical Reviews
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