85,935 research outputs found
Comment on "Spectroscopic Evidence for Multiple Order Parameter Components in the Heavy Fermion Superconductor CeCoIn"
Recently, Rourke et al. reported point-contact spectroscopy results on the
heavy-fermion superconductor CeCoIn [1]. They obtained conductance spectra
on the c-axis surfaces of CeCoIn single crystals. Their major claims are
two-fold: CeCoIn has i) d-wave pairing symmetry and ii) two coexisting
order parameter components. In this Comment, we show that these claims are not
warranted by the data presented. [1] Rourke et al., Phys. Rev. Lett. 94, 107005
(2005).Comment: accepted for publication in Phys. Rev. Lett., final for
Report on objective ride quality evaluation
The correlation of absorbed power as an objective ride measure to the subjective evaluation for the bus data was investigated. For some individual bus rides the correlations were poor, but when a sufficient number of rides was used to give reasonable sample base, an excellent correlation was obtained. The following logarithmical function was derived: S = 1.7245 1n (39.6849 AP), where S = one subjective rating of the ride; and AP = the absorbed power in watts. A six-degree-of-freedom method developed for aircraft data was completed. Preliminary correlation of absorbed power with ISO standards further enhances the bus ride and absorbed power correlation numbers since the AP's obtained are of the same order of magnitude for both correlations. While it would then appear that one could just use ISO standards, there is no way to add the effect of three degrees of freedom. The absorbed power provides a method of adding the effects due to the three major directions plus the pitch and roll
A key to room-temperature ferromagnetism in Fe-doped ZnO: Cu
Successful synthesis of room-temperature ferromagnetic semiconductors,
ZnFeO, is reported. The essential ingredient in achieving
room-temperature ferromagnetism in bulk ZnFeO was found to be
additional Cu doping. A transition temperature as high as 550 K was obtained in
ZnFeCuO; the saturation magnetization at room
temperature reached a value of per Fe. Large
magnetoresistance was also observed below K.Comment: 11 pages, 4 figures; to appear in Appl. Phys. Let
Analysis of recent type Ia supernova data based on evolving dark energy models
We study characters of recent type Ia supernova (SNIa) data using evolving
dark energy models with changing equation of state parameter w. We consider
sudden-jump approximation of w for some chosen redshift spans with double
transitions, and constrain these models based on Markov Chain Monte Carlo
(MCMC) method using the SNIa data (Constitution, Union, Union2) together with
baryon acoustic oscillation A parameter and cosmic microwave background shift
parameter in a flat background. In the double-transition model the Constitution
data shows deviation outside 1 sigma from LCDM model at low (z < 0.2) and
middle (0.2 < z < 0.4) redshift bins whereas no such deviations are noticeable
in the Union and Union2 data. By analyzing the Union members in the
Constitution set, however, we show that the same difference is actually due to
different calibration of the same Union sample in the Constitution set, and is
not due to new data added in the Constitution set. All detected deviations are
within 2 sigma from the LCDM world model. From the LCDM mock data analysis, we
quantify biases in the dark energy equation of state parameters induced by
insufficient data with inhomogeneous distribution of data points in the
redshift space and distance modulus errors. We demonstrate that location of
peak in the distribution of arithmetic means (computed from the MCMC chain for
each mock data) behaves as an unbiased estimator for the average bias, which is
valid even for non-symmetric likelihood distributions.Comment: 12 pages, 6 figures, published in the Phys. Rev.
Rich variety of defects in ZnO via an attractive interaction between O-vacancies and Zn-interstitials
As the concentration of intrinsic defects becomes sufficiently high in
O-deficient ZnO, interactions between defects lead to a significant reduction
in their formation energies. We show that the formation of both O-vacancies and
Zn-interstitials becomes significantly enhanced by a strong attractive
interaction between them, making these defects an important source of n-type
conductivity in ZnO.Comment: 12 pages, 4 figure
Solar-neutrino reactions on deuteron in effective field theory
The cross sections for low-energy neutrino-deuteron reactions are calculated
within heavy-baryon chiral perturbation theory employing cut-off regularization
scheme. The transition operators are derived up to
next-to-next-to-next-to-leading order in the Weinberg counting rules, while the
nuclear matrix elements are evaluated using the wave functions generated by a
high-quality phenomenological NN potential. With the adoption of the
axial-current-four-nucleon coupling constant fixed from the tritium beta decay
data, our calculation is free from unknown low-energy constants. Our results
exhibit a high degree of stability against different choices of the cutoff
parameter, a feature which indicates that, apart from radiative corrections,
the uncertainties in the calculated cross sections are less than 1 %.Comment: 12 pages, 3 figures. Error estimation of higher order corrections
detaile
Magnetic states and optical properties of single-layer carbon-doped hexagonal boron nitride
We show that carbon-doped hexagonal boron nitride (h-BN) has extraordinary
properties with many possible applications. We demonstrate that the
substitution-induced impurity states, associated with carbon atoms, and their
interactions dictate the electronic structure and properties of C-doped h-BN.
Furthermore, we show that stacking of localized impurity states in small C
clusters embedded in h-BN forms a set of discrete energy levels in the wide gap
of h-BN. The electronic structures of these C clusters have a plethora of
applications in optics, magneto-optics, and opto-electronics
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