14,977 research outputs found
Magnetism as a mass term of the edge states in graphene
The magnetism by the edge states in graphene is investigated theoretically.
An instability of the pseudo-spin order of the edge states induces
ferrimagnetic order in the presence of the Coulomb interaction. Although the
next nearest-neighbor hopping can stabilize the pseudo-spin order, a strong
Coulomb interaction makes the pseudo-spin unpolarized and real spin polarized.
The magnetism of the edge states makes two peaks of the density of states in
the conduction and valence energy bands near the Fermi point. Using a
continuous model of the Weyl equation, we show that the edge-induced gauge
field and the spin dependent mass terms are keys to make the magnetism of the
edge states. A relationship between the magnetism of the edge states and the
parity anomaly is discussed.Comment: 7 pages, 5 figure
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Experimental Study of Dislocation Damping Using a Rock Analogue
In order to explore the effects of dislocations on seismic velocity and attenuation, we conducted a series of forced oscillation and ultrasonic tests on rock analogue samples (polycrystalline borneol) that were pre-deformed under various differential stress âÏ. Additionally, creep experiments were conducted to determine the steady-state flow law for borneol. The dominant deformation mechanism of polycrystalline borneol changes from diffusion to dislocation creep at about âÏ = 2 MPa. At high stresses, power law creep with a stress exponent of âŒ4 was measured. Microstructure of the deformed samples showed wavy grain boundaries due to dislocation-induced migration, and the occasional existence of microcracks. A borneol sample deformed in the dislocation creep regime showed a significant reduction in Youngâs modulus E and a slight increase in attenuation Q^â1 at frequencies lower than 100 Hz, whereas E at ultrasonic frequency (10^6 Hz) did not reduce. Therefore, a major part of the dislocation creep-induced anelastic relaxation is a peak with a characteristic frequency between 100 and 10^6 Hz, which is much higher than the range of grain boundary-induced anelasticity of this material. Further experiments under higher confining pressure are needed to assess the relative contribution from dislocations and microcracks to this peak.JSPS KAKENHI Grant Number JP15K1356
Chiral thermodynamics of dense hadronic matter
We discuss phases of hot and dense hadronic matter using chiral Lagrangians.
A two-flavored parity doublet model constrained by the nuclear matter ground
state predicts chiral symmetry restoration. The model thermodynamics is shown
within the mean field approximation. A field-theoretical constraint on possible
phases from the anomaly matching is also discussed.Comment: 8 pages, 2 figures, to appear in the proceedings of 6th International
Workshop on Critical Point and Onset of Deconfinement (CPOD), 23-29 August
2010 at Joint Institute for Nuclear Research, Dubna, Russi
Gauge field for edge state in graphene
By considering the continuous model for graphene, we analytically study a
special gauge field for the edge state. The gauge field explains the properties
of the edge state such as the existence only on the zigzag edge, the partial
appearance in the -space, and the energy position around the Fermi energy.
It is demonstrated utilizing the gauge field that the edge state is robust for
surface reconstruction, and the next nearest-neighbor interaction which breaks
the particle-hole symmetry stabilizes the edge state.Comment: 9 pages, 5 figure
Observation of the Interference Effect of Electron-Capture X-rays from Radioisotopes
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Weak Magnetic Order in the Bilayered-hydrate NaCoOHO Structure Probed by Co Nuclear Quadrupole Resonance - Proposed Phase Diagram in Superconducting NaCoO HO
A weak magnetic order was found in a non-superconducting bilayered-hydrate
NaCoOHO sample by a Co Nuclear Quadrupole Resonance
(NQR) measurement. The nuclear spin-lattice relaxation rate divided by
temperature shows a prominent peak at 5.5 K, below which a Co-NQR peak
splits due to an internal field at the Co site. From analyses of the Co NQR
spectrum at 1.5 K, the internal field is evaluated to be 300 Oe and is
in the -plane. The magnitude of the internal field suggests that the
ordered moment is as small as using the hyperfine coupling
constant reported previously. It is shown that the NQR frequency
correlates with magnetic fluctuations from measurements of NQR spectra and
in various samples. The higher- sample has the stronger
magnetic fluctuations. A possible phase diagram in NaCoOHO is depicted using and , in which the crystal distortion
along the c-axis of the tilted CoO octahedron is considered to be a
physical parameter. Superconductivity with the highest is seemingly
observed in the vicinity of the magnetic phase, suggesting strongly that the
magnetic fluctuations play an important role for the occurrence of the
superconductivity.Comment: 5 pages, 6 figures, submitted to J. Phys. Soc. Jp
Spectral density analysis of time correlation functions in lattice QCD using the maximum entropy method
We study various aspects of extracting spectral information from time
correlation functions of lattice QCD by means of Bayesian inference with an
entropic prior, the maximum entropy method (MEM). Correlator functions of a
heavy-light meson-meson system serve as a repository for lattice data with
diverse statistical quality. Attention is given to spectral mass density
functions, inferred from the data, and their dependence on the parameters of
the MEM. We propose to employ simulated annealing, or cooling, to solve the
Bayesian inference problem, and discuss practical issues of the approach.Comment: 11 pages, 30 figure files (eps), some references added and updated,
requires REVTeX 4.0 and prerequisites (AMS-LaTeX 2.0, graphicx, dcolumn, bm)
see http://publish.aps.org/revtex4
Minimum-error discrimination between symmetric mixed quantum states
We provide a solution of finding optimal measurement strategy for
distinguishing between symmetric mixed quantum states. It is assumed that the
matrix elements of at least one of the symmetric quantum states are all real
and nonnegative in the basis of the eigenstates of the symmetry operator.Comment: 10 page
Exceptional orthogonal polynomials and the Darboux transformation
We adapt the notion of the Darboux transformation to the context of
polynomial Sturm-Liouville problems. As an application, we characterize the
recently described Laguerre polynomials in terms of an isospectral
Darboux transformation. We also show that the shape-invariance of these new
polynomial families is a direct consequence of the permutability property of
the Darboux-Crum transformation.Comment: corrected abstract, added references, minor correction
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