排序方式: 共有130条查询结果,搜索用时 15 毫秒
61.
A.G. Kuchin A.S. ErmolenkoYu.A. Kulikov V.I. KhrabrovE.V. Rosenfeld G.M. MakarovaT.P. Lapina Ye.V. Belozerov 《Journal of magnetism and magnetic materials》2006
The magnetic properties have been studied for the series of RNi5−xCux intermetallics with R=Y, La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, Lu; x ?2.5. Compositional dependences of magnetic susceptibility for the Pauli paramagnets (R=Y, La, Ce, Lu) and the Curie temperature for ferromagnets (R=Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm) have maximum at x=0.2–0.4 and 1, respectively. The substitution of Cu for Ni is accompanied by decreasing spontaneous magnetic moment and increasing coercive force of all ferromagnetic RNi5−xCux but GdNi5−xCux. These results are explained in the frame of band magnetism, random local crystal field, and domain wall pinning theories. 相似文献
62.
We present the theoretical investigation of photoelectron spectroscopy resulting from the strong field induced multiphoton ionization in a typical three-level ladder-style system. Our theoretical results show that the photo-electron spectral structure can be alternatively steered by spectral phase modulation. This physical mechanism for strong field quantum control is explicitly exploited by the time-dependent dressed state population. It is concluded that the phase-shaped laser pulses can be used to selectively manipulate the multiphoton ionization process in complicated quantum systems. 相似文献
63.
Ahmad Yazdani 《Journal of magnetism and magnetic materials》2009,321(24):3990-3996
In this paper it is demonstrated that the second phase transition of Gd2In intermetallic compound gets eliminated by diluting Gd2−x(LaY)xIn at a critical composition of x=0.5. The exchange coupling for intra-cluster interactions is estimated in the correlation ranges of 3.3 Å<RC<3.6 Å (anisotropic source) and for inter-cluster interactions in the ranges of RC>4 Å where the correlation length is defined as . The sign and strength of the exchange coupling are identified by the eigenvalues λ(k) and are obtained from zeros of the 4×4 matrix of JijRR′ along the three directions of the reciprocal lattice for each dilution (x=0.25, 0.5, 0.75, 1). The transition temperature is calculated using the minimum eigenvalue λmin (k=0, π) which agrees with the experiment. Magnetic field and temperature dependence of the magnetization and electrical resistivity measurements show that: (i) Elimination of the AFM phase is caused by breaking of some FM short-range exchange couplings, and (ii) Conduction electrons order antiferromagnetically at low temperatures and ferromagnetically at high temperatures. 相似文献
64.
N. Sanner O. Utéza B. Bussiere G. Coustillier A. Leray T. Itina M. Sentis 《Applied Physics A: Materials Science & Processing》2009,94(4):889-897
The paper is focused on the importance of accurate determination of surface damage/ablation threshold of a dielectric material
irradiated with femtosecond laser pulses. We show that different damage characterization techniques and data treatment procedures
from a single experiment provide complementary physical results characterizing laser–matter interaction. We thus compare and
discuss two regression techniques, well adapted to the measurement of laser ablation threshold, and a statistical approach
giving the laser damage threshold and further information concerning the deterministic character of femtosecond damage. These
two measurements are crucial for laser micromachining processes and high peak-power laser technology in general. 相似文献
65.
The optical absorption and the luminescence emission were investigated in AgClxBr1−x crystals (0<x<1) doped with Tb3+ ions and in fibers extruded from these crystals. Strong luminescence emission in the middle infrared (MIR) in the spectral range 4.2-5.6 μm was observed for the first time in such crystals and fibers.1 Various optical parameters were calculated for the Tb3+-doped crystals, using the Judd-Ofelt approximation. The measured and the calculated results have indicated that these doped crystals could be used for the development of solid-state lasers or fiber lasers operating in the middle infrared. 相似文献
66.
Chong-Geng Ma Shang-Da Xia M.F. Reid 《Journal of Physics and Chemistry of Solids》2008,69(10):2578-2583
The application of point-group coupling coefficients to the modeling of fN↔fN−1d transitions is discussed. There are several possible coupling schemes for the states of the fN−1d configuration. Formulae for matrix elements of the Hamiltonian for the fN−1d configuration and the relative line strengths for fN↔fN−1d transitions are derived. As an example, the f-d absorption spectrum of the crystal Yb2+: SrCl2 is calculated using coupling coefficients based on the software developed by Butler and co-workers, which makes use of the Racah-Wigner calculus. The advantages and disadvantages of various coupling schemes are demonstrated. These coupling schemes are related to the simple model for f-d transitions. 相似文献
67.
O. Lopez A. Amy-Klein C. Daussy C. Chardonnet F. Narbonneau M. Lours G. Santarelli 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,48(1):35-41
RF frequency transfer over an urban 86 km fibre has
been demonstrated with a resolution of 2×10-18 at one day
measuring time using an optical compensator. This result is obtained with a
reference carrier frequency of 1 GHz, and a rapid scrambling of the
polarisation state of the input light in order to reduce the sensitivity to
the polarisation mode dispersion in the fibre. The limitation due to the
fibre chromatic dispersion associated with the laser frequency fluctuations
is highlighted and analyzed. A preliminary test of an extended compensated
link over 186 km using optical amplifiers gives a resolution below
10-17 at 1 day. 相似文献
68.
P. Balling P. Křen 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,48(1):3-10
This paper describes the results of absolute frequency
measurements of primary wavelength standards 633 nm, 543 nm, 532 nm, (iodine
stabilized) and 1540 nm (acetylene stabilized) in CMI. The values obtained
with Menlo Systems femtosecond frequency comb in CMI are compared with
previous measurements of the same standards in BIPM, BEV and MPQ. Measured
sub-Doppler linewidths and relative intensities of several hyperfine
spectral components of iodine molecule are also presented. 相似文献
69.
H. Hess K.R. Asmis T. Leisner L. Wöste 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,16(1):145-149
We present results on the ultrafast dynamics of mass-selected neutral Ag4 clusters using NeNePo (negative ion - neutral - positive ion) femtosecond pump-probe spectroscopy. One-color pump-probe spectra
of the Ag4
-/Ag4/Ag4
+ system measured at 385 nm and an internal cluster temperature of 20 K display a complex beat structure over more than 60
ps. The oscillatory structure is attributed to vibrational wave packet dynamics in an excited “dark" state of neutral Ag4. A dominant 740 fs wave packet period as well as wave packet dephasing and rephasing are observed in the spectra. Fourier
analysis of the spectra yields a group of frequencies centered around 45 cm-1 and an anharmonicity χ
e2νχ
eχ
e of 2.65 cm-1 for the active vibrational mode.
Received 30 November 2000 相似文献
70.
A.G. Kuchin N.V. Mushnikov M.I. Bartashevich O. Prokhnenko V.I. Khrabrov T.P. Lapina 《Journal of magnetism and magnetic materials》2007
Magnetic properties of the Ce2Fe17−xMnx, x=0–2, alloys in magnetic fields up to 40 T are reported. The compounds with x=0.5–1 are helical antiferromagnets and those with 1<x?2 are helical ferromagnets or helical antiferromagnets at low and high T, respectively. Mn ions in the system carry average magnetic moment of 3.0±0.2 μB that couple antiparallelly to the Fe moments. Easy-plane magnetic anisotropy in the Ce2Fe17−xMnx compounds weakens upon substitution of Mn for Fe. The absolute value of the first anisotropy constant in the Ce2Fe17−xMnx helical ferromagnets decreases slower with increasing temperature than that calculated from the third power of the spontaneous magnetization. Noticeable magnetic hysteresis in the Ce2Fe17−xMnx, x=0.5–2, helical magnets over the whole range of magnetic fields reflects mainly irreversible deformation of the helical magnetic structure during the magnetization of the compounds. A contribution from short-range order (SRO) magnetic clusters to the magnetic hysteresis of the helical magnets has been also estimated. 相似文献