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E. Goering M. Justen J. Geissler U. Rüdiger M. Rabe G. Güntherodt G. Schütz 《Applied Physics A: Materials Science & Processing》2002,74(6):747-753
Highly a-axis-textured CrO2 films have been deposited on Al2O3 (0001) substrates by chemical vapor deposition. CrO2 has been found to have highly a-axis (010)-oriented columnar growth on a Cr2O3 (0001) initial layer. The six-fold surface symmetry of the Cr2O3 initial layer leads to three equivalent in-plane orientations of the a-axis-oriented CrO2 unit cell. We report Cr L2,3 X-ray magnetic circular dichroism data along the surface normal and at 60° off-normal sample orientation. For a 60° sample
alignment, a strong increase of the projected orbital moment could be observed for unoccupied majority t2g states using moment analysis. Therefore, the c axis is identified as the intrinsic magnetic easy axis of CrO2. In addition, a small spin moment and a very strong magnetic dipole term Tz have been found.
Received: 8 January 2002 / Accepted: 8 January 2002 相似文献
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We develop an effective numerical method of studying large-time properties of reversible reaction-diffusion systems of type
A + B ↔ C with initially separated reactants. Using it we find that there are three types of asymptotic reaction zones. In particular
we show that the reaction rate can be locally negative and concentrations of species A and B can be nonmonotonic functions
of the space coordinate x, locally significantly exceeding their initial values.
Received 6 June 2002 / Received in final form 20 January 2003 Published online 7 May 2003 相似文献
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《The European Physical Journal A - Hadrons and Nuclei》2003,17(2):241-244
The helicity dependence of the γ
p↦pη reaction has been measured for the first time at a center-of-mass angle θ*
η = 70° in the photon energy range from 780 MeV to 790 MeV. The experiment, performed at the Mainz microtron MAMI, used a 4π-detector
system, a circularly polarized, tagged photon beam, and a longitudinally polarized frozen-spin target. The helicity 3/2 cross-section
is found to be small and the results for helicity 1/2 agree with predictions from the MAID analysis.
Received: 19 December 2002 / Accepted: 10 March 2003 / Published online: 20 May 2003 相似文献
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M. Mahjour-Shafiei H.R. Amir-Ahmadi J.C.S. Bacelar R. Castelijns K. Ermisch E.D. van Garderen I. Gašparić M.N. Harakeh N. Kalantar-Nayestanaki M. Kiš H. Löhner O. Scholten 《Physics letters. [Part B]》2006
A series of nucleon–nucleon bremsstrahlung (NNγ) experiments at 190 MeV incident beam energy have been performed at KVI in order to gain more insight into the dynamics governing the bremsstrahlung reaction. After initial measurements wherein the bremsstrahlung process was studied far away from the elastic limit, a new study was used to probe the process nearer to the elastic limit by measuring at lower photon energies. Measured cross sections and analyzing powers are compared with the predictions of a microscopic model and those of two soft-photon models. The theoretical calculations overestimate the data by up to ≈30%, for some kinematics. 相似文献
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C. Van den Abeele D. Ryckbosch G. De Meyer J. F. Dias L. Van Hoorebeke R. Van de Vyver J. -O. Adler K. Hansen L. Isaksson H. Ruijter P. Svensson B. Schröder 《Zeitschrift für Physik A Hadrons and Nuclei》1995,351(2):133-136
The values of the angle-integrated cross section for the decay to various low-lying states in39K following the40Ca(,) reaction at a mean photon energy of 60 MeV are reported on, together with the values of the reduced Legendre coefficientsa
i
. The40Ca(,gp) and40Ca(,n) reactions yield the same angular cross-section values and these agree with the corresponding RPA-calculations.Senior Research Associate NFWO 相似文献
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M. Sajid 《Numerical Methods for Partial Differential Equations》2010,26(1):221-228
This article investigates the analytic solution for the flow of a third grade fluid past an infinite porous plate. The method of parameter differentiation is used to linearized the governing flow equation. The solution of the obtained linear equation is developed by differential transform method in combination with the method of superposition. The obtained results are compared with existing results in the literature and an excellent agreement is found. This shows that the parameter differentiation is a powerful technique for solving nonlinear problems. © 2009 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2010 相似文献
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Data for coherent photoproduction of π0 mesons from nuclei ( 12C, 40Ca, 93Nb, natPb), recently measured with the TAPS detector at the Mainz MAMI accelerator, have been analyzed in view of the mass form factors
of the nuclei. The form factors have been extracted in plane-wave approximation of the A(γ,π0)A reaction and corrected for final-state interaction effects with the help of distorted-wave impulse approximations. Nuclear
mass rms radii have been calculated from the slope of the form factors for q2 → 0. Furthermore, the Helm model (hard-sphere form factor folded with Gaussian) was used to extract diffraction radii from
the zeroes of the form factor and skin thicknesses from the position and height of its first maximum. The diffraction radii
from the Helm model agree with the corresponding charge radii obtained from electron scattering experiments within their uncertainties
of a few per cent. The rms radii from the slope of the form factors are systematically lower by up to 5% for PWIA and up to
10% for DWIA. Also the skin thicknesses extracted from the Helm model are systematically smaller than their charge counterparts. 相似文献
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C. Giusti F. D. Pacati M. Schwamb S. Boffi 《The European Physical Journal A - Hadrons and Nuclei》2007,33(1):29-38
Results for the cross-sections of the exclusive 16O(e, e'pn)14N and 16O(γ, pn)14N knockout reactions are presented and discussed in different kinematics. In comparison with earlier work, a complete treatment
of the center-of-mass (CM) effects in the nuclear one-body current is considered in connection with the problem of the lack
of orthogonality between initial bound and final scattering states. The effects due to CM and orthogonalization are investigated
in combination with different treatments of correlations in the two-nucleon overlap function and for different parametrizations
of the two-body currents. The CM effects lead in super-parallel kinematics to a dramatic increase of the 16O(e, e'pn) cross-section to the 12
+ excited state (3.95MeV) of 14N . In all the situations considered the results are very sensitive to the treatment of correlations. A crucial role is played
by tensor correlations, but also the contribution of long-range correlations is important. 相似文献
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