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951.
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
952.
A. V. Lebedev 《Acoustical Physics》2002,48(3):339-346
The possibility of using the resonant acoustic spectroscopy method for testing the internal state of rock is considered. This method can be used for the determination of the concentration of defects and their spatial distribution. A rock specimen with defects is characterized by a high loss of vibrational energy, which leads to the overlapping of the resonant responses. In this case, the complex resonant frequencies are determined as the parameters of a model that describes the measured transfer function of the response of the mechanical system. The linearity of the vibratory system is used as the a priori information for presetting the functional dependences of the model. An algorithm is developed for the determination of the parameters of the resonances in conditions of their partial overlapping. Examples are presented to demonstrate the possibility of analyzing the complex elastic constant tensor of rock by the acoustic spectroscopy method. The proposed method of experimental data processing provides the possibility for the determination of the weak anisotropy that occurs in the velocity of sound because of a partial fracture of rock. 相似文献
953.
The statistical characteristics of conditional time before ruin of an insurance company, including the distribution function of conditional time and its moments are examined. 相似文献
954.
A. P. Solov’ev M. I. Perchenko Yu. P. Sinichkin O. V. Zyuryukina 《Technical Physics》2002,47(8):996-1001
An expression for a signal at the ultrasonic frequency from a photodetector arising when diffraction waves at the cathode
mix is obtained for the case when the optical and acoustic beams are space-limited and Bragg angles are small. The alternating
current generated when the scattering medium is crossed by a focused 3-MHz ultrasonic beam and illuminated by a cw He-Ne laser
is measured. Satisfactory agreement between experimental results and those calculated from the formulas obtained indicates
that our model treating acoustooptical interaction in the medium in terms of Raman-Nath diffraction is valid. Conditions for
measuring the alternating current (which is a parameter of acoustooptical imaging) that are optimal from the viewpoint of
maximizing the signal and signal-to-noise ratio are predicted theoretically and corroborated experimentally. 相似文献
955.
Ben-Yuan Gu Yao Lu Tzong-Jer Yang 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,26(4):493-502
We present numerical investigations of the transmission properties of electrons in a normal quantum wire tangentially attached
to a superconductor ring threaded by magnetic flux. A point scatterer with a δ -function potential is placed at node to model
scattering effect. We find that the transmission characteristics of electrons in this structure strongly depend on the normal
or superconducting state of the ring. The transmission probability as a function of the energy of incident electrons, in the
case of a superconductor ring threaded by one quantum magnetic flux, emerges one deep dip, imposed upon the first broad bump
in spectrum. This intrinsic conductance dip originates from the superconductor state of the ring. When increasing the magnetic
flux from one quantum magnetic flux to two, the spectrum shifts toward higher energy region in the whole. This conductance
dip accordingly shifts and appears in the second bump. In the presence of a point-scatterer at the node, the spectrum is substantially
modified. Based on the condition of the formation of the standing wave functions in the ring and the broken of the time-reserve
symmetry of Schr?dinger equation after switching magnetic flux, the characteristics of transmission of electrons in this structure
can be well understood.
Received 6 November 2001 相似文献
956.
The potential and polarization distributions in a planar emitting layer of PLZT-9/65/35 ferroelectric ceramic with a set of conductive strip electrodes on the emitting side and a continuous electrode on the opposite side are studied by numerical methods. The state arising immediately after polarization switching at the leading edge of an applied voltage pulse (i.e., before the polarization charges are screened by free charges) is considered. When the pulsed field strength far exceeds the double coercive field, regions with alternating polarization are found to form in the surface layer between the strips. The normal component of the polarization at its maxima is close to saturation. The electric field on both sides of the surface varies as the polarization vector and reaches 200 kV/cm. At surface microirregularities, the electric field strength is much higher. This means that field emission is responsible for electron escape from the ferroelectric ceramic during pulsed polarization switching. 相似文献
957.
Exact solutions of the Lagrange equations in the Logunov metric are found in the context of classical gravitation theory. 相似文献
958.
R. A. Kotel’nikova G. N. Bogdanov G. V. Zotina V. S. Romanova Z. N. Parnes 《Physics of the Solid State》2002,44(3):576-577
Efficient quenching of eosin phosphorescence by amino-acid derivatives of fullerene (AADFs) such as C60-alanine and C60-glycine in aqueous solutions indicates the possibility of transferring electrons from eosin to fullerene upon collisions or in the exciplex state. To investigate electron transfer in the protein structure, we studied the process of incorporation of C60-alanine and C60-glycine into the heme pocket of myoglobin by controlling Förster quenching. The dissociation constant for the protein-AADF complex was estimated. 相似文献
959.
The stroboscopic method was applied to study the evolution of dynamic spiral domains in garnet ferrite films in an ac magnetic field. The spiral-domain shape was shown to change significantly within a field period; the basic shape transformations take place in the phase range ?π/4 to +π/4 with respect to the polarity inversion time. During the spiral-domain formation or decay, the area and shape of a hysteresis loop of the film region containing the domain gradually change. The upper boundary of the frequency range in which spiral domains form was established to be associated with transformations of the domain wall structure. 相似文献
960.
V. F. Dmitriev 《Technical Physics》2002,47(8):1024-1031
A synthesis method for ladder-type filters based on SAW resonators is described. SAW devices are designed with modified equations for coupled waves. Nomograms for choosing the geometry of the filters on ST, X-cut quartz and on 36° Y, X-cut LiTaO3 substrates are presented. Theoretical results are compared with experimental data. 相似文献