1,487 research outputs found
Fabrication of (Ga,Mn)N nanowires with room temperature ferromagnetism using nitrogen plasma
Ferromagnetic properties of (Ga,Mn)N nanowires were examined by treating with nitrogen plasma at 200 ??C. Nanowires grown by chemical vapor deposition were n-type and no secondary phases were found. The magnetic moment increased and was maintained at room temperature by this treatment. Synchrotron radiation photoemission spectroscopy revealed that Ga vacancies significantly increased, but N vacancies decreased by plasma treatment, leading to a decrease of MnGa-VN complex and the enhancement of Mn activation.open111
Enhancement of magnetic properties by nitrogen implantation to Mn-implanted p-type GaN
N and Mn ions were co-implanted into p-type GaN and subsequently annealed at 700-900degreesC. Compared with Mn-implanted sample, the (Mn+N)-implanted sample revealed a larger ferromagnetic signal. This was attributed to the increase of Ga-Mn magnetic phases. Mn-N compounds, such as Mn6N2.58 and Mn3N2, decreased and the resistivity significantly increased, meaning a reduction of N vacancies. It is suggested that enhancement in ferromagnetic properties in the (Mn+N)-implanted GaN originated from the reduction of N vacancies and the increase of Ga-Mn magnetic phases.open293
Microstructural, optical, and magnetic properties of Mn-implanted p-type GaN
The microstructural, optical and magnetic properties of Mn-implanted p-type GaN were investigated. Dilute magnetic semiconductor was achieved by implanting Mn ions into p-type GaN and subsequently annealing. The Ga-Mn magnetic phases contributing to the ferromagnetic property were produced after annealing Mn-implanted p-type GaN below 800??C.open151
Spectra of random Hermitian matrices with a small-rank external source: supercritical and subcritical regimes
Random Hermitian matrices with a source term arise, for instance, in the
study of non-intersecting Brownian walkers \cite{Adler:2009a, Daems:2007} and
sample covariance matrices \cite{Baik:2005}.
We consider the case when the external source matrix has two
distinct real eigenvalues: with multiplicity and zero with multiplicity
. The source is small in the sense that is finite or , for . For a Gaussian potential, P\'ech\'e
\cite{Peche:2006} showed that for sufficiently small (the subcritical
regime) the external source has no leading-order effect on the eigenvalues,
while for sufficiently large (the supercritical regime) eigenvalues
exit the bulk of the spectrum and behave as the eigenvalues of
Gaussian unitary ensemble (GUE). We establish the universality of these results
for a general class of analytic potentials in the supercritical and subcritical
regimes.Comment: 41 pages, 4 figure
Seasonal Variation in Carcass Characteristics of Korean Cattle Steers
Climate temperature affects animal production. This study was conducted to evaluate whether climatic conditions affect beef carcass characteristics of Korean cattle steers. The monthly carcass characteristics of Korean cattle steers (n = 2,182,415) for 8 yr (2006 through 2013) were collected from the Korean Institute for Animal Products Quality Evaluation. Daily climate temperature (CT) and relative humidity (RH) data were collected from the Korean Meteorological Administration. Weather conditions in South Korea during summer were hot and humid, with a maximum temperature of 28.4°C and a maximum RH of 91.4%. The temperature-humidity index (THI), calculated based on CT and RH, ranges from 73 to 80 during summer. Winter in South Korea was cold, with a minimum temperature of −4.0°C and a wind-chill temperature of −6.2°C. Both marbling score (MS) and quality grade (QG) of Korean cattle steer carcasses were generally best (p0.05) with CT. Yield grade (YG) of Korean cattle steer carcasses was lowest (p<0.05) in winter (November to January) and highest in spring and summer (May to September). A correlation analysis revealed that YG frequency was strongly correlated (r≥0.71; p<0.01) with CT and THI values. The rib eye area, a positive YG parameter, was not associated with CT. Backfat thickness (BT), a negative YG factor, was highest in winter (November and December). The BT was strongly negatively correlated (r≤−0.74; p<0.01) with CTs. Therefore, the poor YG during winter is likely due in part to the high BT. In conclusion, YG in Korean cattle steer carcasses was worst in winter. QGs were not associated with winter or summer climatic conditions
The k-Point Random Matrix Kernels Obtained from One-Point Supermatrix Models
The k-point correlation functions of the Gaussian Random Matrix Ensembles are
certain determinants of functions which depend on only two arguments. They are
referred to as kernels, since they are the building blocks of all correlations.
We show that the kernels are obtained, for arbitrary level number, directly
from supermatrix models for one-point functions. More precisely, the generating
functions of the one-point functions are equivalent to the kernels. This is
surprising, because it implies that already the one-point generating function
holds essential information about the k-point correlations. This also
establishes a link to the averaged ratios of spectral determinants, i.e. of
characteristic polynomials
Vicious Walkers and Hook Young Tableaux
We consider a generalization of the vicious walker model. Using a bijection
map between the path configuration of the non-intersecting random walkers and
the hook Young diagram, we compute the probability concerning the number of
walker's movements. Applying the saddle point method, we reveal that the
scaling limit gives the Tracy--Widom distribution, which is same with the limit
distribution of the largest eigenvalues of the Gaussian unitary ensemble.Comment: 23 pages, 5 figure
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