14,404 research outputs found
Crustal interpretation of the MAGSAT data in the continental United States
The processing of MAGSAT scalar data to construct a crustal magnetic anomaly map over the continental U.S. involves removal of the reference field model, a path-by-path subtraction of a low order polynomial through a least-squares fit to reduce orbital offset errors, and a two dimensional spectral filtering to mitigate the spectral bias induced by the path-by-path orbital correction scheme. The resultant anomaly map shows reasonably good correlations with an aeromagnetic map derived from the project MAGNET. Prominent satellite magnetic anomalies are identified in terms of geological provinces and age boundaries. An inversion method was applied to MAGSAT data which produces both the Curie depth topography and laterally varying magnetic susceptibility of the crust. A contoured Curie depth map thus derived shows general agreements with a crustal thickness map based on seismic data
Drastic Reduction of Shot Noise in Semiconductor Superlattices
We have found experimentally that the shot noise of the tunneling current
through an undoped semiconductor superlattice is reduced with respect to the
Poissonian noise value , and that the noise approaches 1/3 of that value
in superlattices whose quantum wells are strongly coupled. On the other hand,
when the coupling is weak or when a strong electric field is applied to the
superlattice the noise becomes Poissonian. Although our results are
qualitatively consistent with existing theories for one-dimensional mulitple
barriers, the theories cannot account for the dependence of the noise on
superlattice parameters that we have observed.Comment: 4 Pages, 3Figure
Higgs bosons of a supersymmetric model at the ILC
We study the scalar Higgs sector of the next-to-minimal supersymmetric
standard model with an extra U(1), which has two Higgs doublets and a Higgs
singlet, in the light leptophobic scenario where the extra neutral gauge
boson does not couple to charged leptons. In this model, we find that the
sum of the squared coupling coefficients of the three neutral scalar Higgs
bosons to , normalized by the corresponding SM coupling coefficient is
noticeably smaller than unity, due to the effect of the extra U(1), for a
reasonable parameter space of the model, whereas it is unity in the
next-to-minimal supersymmetric standard model. Thus, these two models may be
distinguished if the coupling coefficients of neutral scalar Higgs bosons to
are measured at the future International Linear Collider by producing them
via the Higgs-strahlung, fusion, and fusion processes.Comment: 12 pages, 2 figures, 1 table, PR
Infrared Hall conductivity of NaCoO
We report infrared Hall conductivity of
NaCoO thin films determined from Faraday rotation angle
measurements. exhibits two types of hole
conduction, Drude and incoherent carriers. The coherent Drude carrier shows a
large renormalized mass and Fermi liquid-like behavior of Hall scattering rate,
. The spectral weight is suppressed and disappears at T
= 120K. The incoherent carrier response is centered at mid-IR frequency and
shifts to lower energy with increasing T. Infrared Hall constant is positive
and almost independent of temperature in sharp contrast with the dc-Hall
constant.Comment: 5 Pages, 5 Figures. Author list corrected in metadata only, paper is
unchange
Dirac quasinormal frequencies in Schwarzschild-AdS space-time
We investigate the quasinormal mode frequencies for the massless Dirac field
in static four dimensional space-time. The separation of the Dirac
equation is achieved for the first time in space. Besides the relevance
that this calculation can have in the framework of the correspondence
between M-theory on and SU(N) super Yang-Mills theory on
, it also serves to fill in a gap in the literature, which has only been
concerned with particles of integral spin .Comment: 13 pages, 6 figure
Unusual superexchange pathways in a Ni triangular lattice of NiGaS with negative charge-transfer energy
We have studied the electronic structure of the Ni triangular lattice in
NiGaS using photoemission spectroscopy and subsequent model
calculations. The cluster-model analysis of the Ni 2 core-level spectrum
shows that the S 3 to Ni 3 charge-transfer energy is -1 eV and the
ground state is dominated by the configuration ( is a S 3 hole).
Cell perturbation analysis for the NiS triangular lattice indicates that
the strong S 3 hole character of the ground state provides the enhanced
superexchange interaction between the third nearest neighbor sites.Comment: 10 pages, 5 figures, accepted to PR
(Non)-Renormalization of the Chiral Vortical Effect Coefficient
We show using diagramtic arguments that in some (but not all) cases, the
temperature dependent part of the chiral vortical effect coefficient is
independent of the coupling constant. An interpretation of this result in terms
of quantization in the effective 3 dimensional Chern-Simons theory is also
given. In the language of 3D dimensionally reduced theory, the value of the
chiral vortical coefficient is related to the formula . We also show that in the presence of dynamical gauge fields, the CVE
coefficient is not protected from renormalization, even in the large limit.Comment: 11 pages, 3 figures. Version 2 corrects an error and calculates
leading radiative correctio
Signature of Carrier-Induced Ferromagnetism in Ti_{1-x}Co_{x}O_{2-delta}: Exchange Interaction Between High-Spin Co 2+ and the Ti 3d Conduction Band
X-ray photoemission spectroscopy measurements were performed on thin-film
samples of rutile Ti_{1-x}Co_{x}O_{2-delta} to reveal the electronic structure.
The Co 2p core level spectra indicate that the Co ions take the high-spin Co 2+
configuration, consistent with substitution on the Ti site. The high spin state
and the shift due to the exchange splitting of the conduction band suggest
strong hybridization between carriers in the Ti 3d t2g band and the t2g states
of the high-spin Co 2+. These observations support the argument that room
temperature ferromagnetism in Ti_{1-x}Co_{x}O_{2-delta} is intrinsic.Comment: 4 pages, 5 figures. Accepted for publication in Physical Review
Letter
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