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1.
Energy characteristics of Si1–x
Ge
x
–Si quantum-size structures with single quantum wells were calculated numerically based on a four-band k·p method. Analytical expressions for the Luttinger parameters are obtained as functions of the component composition of Si1–x
Ge
x
compounds. Analytical expressions for the energy ħω of optical band-to-band transitions are obtained in an effective mass
approximation and agree well with numerical calculations by the k·p method. This allows one to determine accurately a range of changes while varying the component compositions and thickness
of the active and barrier layers. 相似文献
2.
R. Fermento J. B. González-Díaz A. Cebollada G. Armelles M. Díaz L. Martínez E. Román Y. Huttel C. Ballesteros 《Journal of nanoparticle research》2011,13(6):2653-2659
The optical and magneto-optical properties of hybrid Co–SiOx systems are studied as a function of Co concentration. The structures were prepared by alternate depositions of SiOx thin films and layers of 10-nm-diameter Co nanoparticles produced by an Ion Cluster Source. Both optical and magneto-optical
constants of the system gradually increase with the amount of Co, though maintaining low optical absorption values in the
visible range. The experimental results are well reproduced assuming that the nanoparticles have a cobalt core (7–8 nm in
diameter) surrounded by a cobalt oxide shell (1–2 nm thick). The magneto-optical activity versus optical absorption figure
of merit of this system is compared with other magneto-optical dielectric systems. 相似文献
3.
I. G. Kuleev A. T. Lonchakov I. Yu. Arapova G. I. Kuleev 《Journal of Experimental and Theoretical Physics》1998,87(1):106-114
A new effect of the reduction in the rate of phonon scattering by the spatially correlated system of iron ions in HgSe:Fe
crystals is detected experimentally and calculated theoretically. The thermoelectric power is measured using HgSe:Fe samples
with different iron content in the temperature range 7.5–60 K. It is found that the dependence of the thermoelectric power
on iron content exhibits remarkable features at T<10 K: the quantity |α(N
Fe
)| increases as the iron concentration increases to N
Fe
=5×1018 cm−3, reaches a maximum at N
Fe
≈(1–2)×1019 cm−3, but then monotonically decreases with further increases in N
Fe
. It is shown that the obseved increase in the thermoelectric power is due to a reduction in the rate of phonon scattering
by the spatially correlated system of Fe3+ ions. This new effect is analyzed theoretically, and the theoretical results are compared with the experimental data.
Zh. éksp. Teor. Fiz. 114, 191–207 (July 1998) 相似文献
4.
X-ray and neutron diffraction were used to investigate the effect of oxygen and nitrogen atoms on the formation of the intermediate
δ′-cubic (sp. gr. Fd3m) and δ″-tetragonal (sp. gr. P3121) ordered structures in titanium carbide. In TiC0.545O0.08, TiC0.545N0.09 samples that were investigated, the metal atoms were shifted from ideal positions in the direction from vacancies to metalloid
atoms. In the intermediate cubic phase (δ′), the free-parameter values of titanium atoms in the two samples are the same, but are different from their analogous value
in titanium carbide.
Fiz. Tverd. Tela (St. Petersburg) 39, 2207–2209 (December 1997) 相似文献
5.
Nd2CuO4 and La2CuO4 are potential candidates as cathode material for intermediate temperature-solid oxide fuel cells. Nd–Cu and La–Cu oxides
were co-sputtered on rotating substrates from metallic La, Nd and Cu targets in the presence of a reactive argon–oxygen gas
mixture. Structural and chemical features of these films have been determined by X-ray diffraction and energy-dispersive spectroscopy.
Their electrical resistivity was measured using the four-point probe method. As-deposited Nd–Cu based coatings are amorphous
and, after annealing, crystallise in K2NiF4+
δ
-type structure for Nd/Cu atomic ratio of 2, with more or less Nd2O3 or CuO, depending on whether Nd or Cu is in excess, respectively. As-deposited La–Cu based coatings are also amorphous and
crystallise in La2CuO4 for La/Cu >2 or in LaCuO3±δ
perovskite-type structure when Cu is in excess. The electrical measurements show a clear relation between resistivity and
structure of the coatings. After annealing, crystallised neodymium-based coatings show higher resistivity than lanthanum-based
ones. Finally, LaCuO3±δ
exhibit higher resistivity than La2CuO4.
Paper presented at the 11th EuroConference on the Science and Technology of Ionics, Batz-sur-Mer, Sept. 9–15, 2007. 相似文献
6.
An investigation is made of the diffusion of antimony through the bulk and along grain boundaries in copper bicrystals containing
a symmetric 〈100〉 misorientation boundary with misorientation angles from 20 to 37.2°. The bicrystals are grown by the method
of horizontal zone recrystallization. The temperature range for these studies is 480–580 °C, where the solubility of Sb in
Cu is about 6 atomic % and practically temperature-independent. The concentration profiles are obtained by x-ray spectral
microanalysis, and the grain-boundary diffusion parameters are computed by the method of Whipple and Suzuoka. The orientation
dependence of the triple product P=sδD
b
(where s is the segregation coefficient, δ the width of the grain boundary, and D
b
the grain-boundary diffusion coefficient) is nonmonotonic, with a maximum for the special ∑5 misorientation boundary (36.9°).
The effective activation energy for grain-boundary diffusion ranges from ∼70 kJ/mol for ∑5 to140 kJ/mol for general boundaries.
Fiz. Tverd. Tela (St. Petersburg) 39, 1153–1157 (July 1997) 相似文献
7.
N. F. Kubrakov A. K. Zvezdin K. A. Zvezdin V. A. Kotov R. Atkinson 《Journal of Experimental and Theoretical Physics》1998,87(3):600-607
The change in the reflectivity of a metallic magnetic multilayer that exhibits giant magnetoresistance for a monochromatic
electromagnetic plane wave with polarization along the magnetization (s polarization) in response to a change from the antiferromagnetic magnetic configuration of the multilayer to the ferromagnetic
configuration is investigated. This magneto-optical effect is treated in the effective-medium approximation, in which the
dielectric constant needed is found analytically with consideration of the interface roughness scattering of electrons. It
is shown in the example of an Fe/Cu multilayer that the effect amounts to ∼0.7%. The representation found for the complex
conductivity is convenient in a special case for investigating the magnetoresistive effect.
Zh. éksp. Teor. Fiz. 114, 1101–1114 (September 1998) 相似文献
8.
A K Sood K Sankaran Y Hariharan S Vijayalakshmi V Sankara Sastry S Kalavathi J Janaki 《Pramana》1988,31(5):389-397
We report infrared absorption of Y1Ba2Cu3O7−δ
as a function of oxygen stoichiometry (0<δ<1) and copper substitution by iron in the spectral range of 450–700 cm−1. The strong bands associated with Cu-O vibrations undergo significant changes in their frequencies and intensities asδ is varied across the orthorhombic to tetragonal phase. These changes coupled with those arising as a result of doping with
iron has helped in identifying the nature of the vibrational modes. 相似文献
9.
E. R. Likhachev S. I. Kurganskii O. I. Dubrovskii A. M. Bugakov 《Physics of the Solid State》1997,39(3):378-380
The results of calculations of the energy band structure of thin films are used to obtain theoretical photoelectron spectra
of the valence band of the compound YBa2Cu3O7−δ
for δ=0 and δ=1 at various photon energies; the spectra are averaged over the photoelectron emission angles. The principal structural features
of the spectra are determined by the d states of copper atoms, while the variation of the shape of the spectra with increasing photon energy is attributed to a
relative decrease in the contribution from the p states of oxygen atoms. The density of d states around the Fermi level for YBa2Cu3O6 films is observed to increase relative to YBa2Cu3O7 films.
Fiz. Tverd. Tela (St. Petersburg) 39, 437–440 (March 1997) 相似文献
10.
S. O. Romanovskii A. V. Sel’kin I. G. Stamov N. A. Feoktistov 《Physics of the Solid State》1998,40(5):814-815
A study is made of the effect of electric fields on the exciton states of β-ZnP2 crystals (T=77 K) in structures with Schottky barriers formed by depositing semitransparent electrically-conducting InSnO2 films on the crystal surface. The observed changes in the exciton optical reflection spectra when an electrical potential
is applied to a barrier are explained by the shift and broadening of the exciton level caused by the Stark effect. The experimental
data are compared with calculations based on a theory of exciton optical reflection from planar spatially nonuniform structures.
Fiz. Tverd. Tela (St. Petersburg) 40, 884–886 (May 1998) 相似文献
11.
We have studied the growth characteristics, structure, and parameters of the epitaxial heterostructures (001)NdBa2Cu3O7−δ
/(100)SrTiO3/(001)NdBa2Cu3O7−δ
grown by laser ablation on a (100)LaAlO3 substrate with a thin (∼2 nm) YBa2Cu3O7−δ
intermediate layer. The use of an YBa2Cu3O7−δ
intermediate layer promotes layered growth of the (200 nm) NdBa2Cu3O7−δ
layer, whose free-surface roughness is 4–5 nm. The resistance of the NdBa2Cu3O7−δ
layers began to fall off abruptly at T=92 K, and at T≈87 K it vanished completely. The critical current density in the NdBa2Cu3O7−δ
layers at T=76 K exceeded 106 cm2 A/cm2. The dielectric constant of the (400 nm) SrTiO3 layer sandwiched between the NdBa2Cu3O7−δ
epitaxial layers grew by roughly threefold as the temperature was lowered in the interval 300–4.2 K. When a bias voltage
of ±2.5V was applied to the NdBa2Cu3O7−δ
electrodes, the relative dielectric constant of the (400 nm) SrTiO3 intermediate layer fell from 1150 to 400 (T=32 K, f=100 kHz). The conductivity of the SrTiO3 intermediate layer in the direction perpendicular to the substrate plane increased with temperature and the electric field
strength.
Fiz. Tverd. Tela (St. Petersburg) 41, 395–403 (March 1999) 相似文献
12.
The precipitation of the fcc γ-phase of iron has been studied by a systematic series of isothermal and isochronal (0–48 h)
heat treatments (300–800°C) on a supersaturated solution ofCuFe containing 3 at% Fe. The optimal conditions (450–600°C) for precipitation of the maximum fraction (90%) of iron attainable
within 48 h in the form of γ-Fe have been delineated from analysis of the room temperature spectra. The time dependence for
formation of γ-Fe precipitates is well described by the equation for long term annealing. An activation energyE
a
≈0.6 eV for the formation of γ-Fe in Cu is obtained. It indicates short range rather than long range diffusion in theCuFe sample studied. 相似文献
13.
B.?A.?Gizhevski? Yu.?P.?Sukhorukov E.?A.?Gan’shina N.?N.?Loshkareva A.?V.?Telegin N.?I.?Lobachevskaya V.?S.?Gaviko V.?P.?Pilyugin 《Physics of the Solid State》2009,51(9):1836-1842
Bulk dense samples of nanostructured yttrium iron garnet Y3Fe5O12 with crystallite sizes of 20–40 nm are prepared by high-pressure torsion from a garnet powder with micron grains. The absorption
and Faraday rotation spectra in the IR range and the transverse Kerr effect spectra in the visible spectral range for these
samples are measured. The absorption and magneto-optical effect spectra are in agreement with the corresponding spectra of
single crystals. The appearance of additional absorption bands at 2 and 3 μm is associated with the violation of the stoichiometry
of the nanogarnet and the possible contamination of the initial material. The specific Faraday rotation in the transparency
window is approximately 1.5 times smaller than the corresponding quantity for single crystals. The extrema in the Kerr effect
spectra coincide with those for single crystals, are smaller in magnitude, and are smeared. On the whole, the prepared bulk
samples are transparent in the IR spectral range and exhibit optical and magneto-optical characteristics comparable to the
corresponding parameters for single crystals. The high density of point defects of the nanogarnet is primarily due to the
violation of the stoichiometry and the valence state of iron ions. 相似文献
14.
V. E. Fortov A. P. Nefedov O. F. Petrov A. A. Samaryan A. V. Chernyshev 《Journal of Experimental and Theoretical Physics》1997,84(2):256-261
The formation of spatially ordered CeO2 particle structures in a thermal plasma at atmospheric pressure and temperatures of 1700–2200 K is studied. The spatial structure
of the particles in the plasma is analyzed using laser time-of-flight counting of individual particles. Probe and optical
diagnostics are used to determine the parameters of the thermal plasma. The CeO2 particles were positively charged (about 103 electronic charges). The resulting Coulomb interaction parameter for the particles is γ
p>120, which corresponds to a highly nonideal plasma.
Zh. éksp. Teor. Fiz. 111, 467–477 (February 1997) 相似文献
15.
The Bloch enhancement factor α(k
f
) of the electric field gradient has been evaluated for the half-filledd-core Fe host metal and completely filledd-core Cu host metal in single orthogonalized plane wave (OPW) approximation. For this purpose the radially-dependent antishielding
factors,γ(r) have been calculated in non-orthogonal Hartree-Fock perturbation theory (NHFPT). The results show that the contributions
of antishielding to α(k
f
) from the plane wave-plane wave part and the core part of the OPW state are individually large but opposite in sign and thereby
lead to partial cancellation. The net effect of antishielding on α(k
f
) is found to be − 5.6% in Fe and 14% in Cu. 相似文献
16.
We have investigated the absorption spectrum of thin films of the superionic conductor RbCu4Cl3I2 synthesized on NaCl crystalline substrates. It is shown that the electron and exciton excitations in the energy interval
3–6 eV are associated with optical transitions in the CuHal sublattice, and the edge of the fundamental band is controlled
by optical transitions in the Cu(II)Hal sublattice. It is found that the large band gap of this compound (E
g
=3.86 eV) in comparison with those of CuCl and CuI is a result of the small number of Cu ions in the second coordination sphere.
The temperature dependence of the spectral position and half-width of the low-temperature exciton band reveals features associated
with the phase transitions γ→β (T
c1=170 K) and β→α (T
c2=220 K) and with disordering of the cation sublattice attendant to the transition to the superionic state.
Fiz. Tverd. Tela (St. Petersburg) 40, 1022–1026 (June 1998) 相似文献
17.
D. I. Bilenko A. A. Sagaidachnyi V. V. Galushka V. P. Polyanskaya 《Technical Physics》2010,55(10):1478-1483
The possibility of multiparametric determination of properties of structures from the data on the dependence of reflectances
R
p
and R
s
for polarized radiation and ratio R
p
/R
s
on the angle of incidence θ and from the angular dependence 1/R
p
(ΔR/Δθ) is investigated. The results of natural and computer experiments revealed a high sensitivity of the angular dependence
R
p
(θ) of the reflectance to the values of optical constants and thickness of layered structures. Quantitative results of multiparametric
measurements are verified by the independent method of spectral ellipsometry. The possibility of multiparametric determination
of the properties and thickness of nanometer dielectric, metallic, and semiconducting layers on various substrates and the
properties of substrates in such structures is established. 相似文献
18.
We present first-principles calculations of the nonlinear optical (NLO) response of a Ni/Cu(001) bilayer. The calculations
are based on the full potential linearized augmented plane wave (FLAPW) method with the additional implementation of spin–orbit
coupling (SOC). On the basis of this set of eigenstates the magneto-optical transition-matrix elements are evaluated. Using
the surface-sheet model the optical reflection properties are determined for the cases of the magnetization vector perpendicular
to the surface (polar magneto-optical configuration (MOC)) and for the in-plane magnetization (longitudinal MOC). The nonlinear
optical susceptibility tensor elements χ(2)
ijk for different magnetization directions as well as the spectral dependence of χ(2)
ijk, the resulting intensities, and Kerr angles are presented for the Ni/Cu(001) bilayer. The results show that the magnetic
tensor elements of the χ(2)
ijk tensor are smaller than the nonmagnetic ones by only one order of magnitude, confirming the important role of magnetic properties
in the NLO response.
Received: 16 October 2001 / Revised version: 8 March 2002 / Published online: 29 May 2002 相似文献
19.
E. S. Demidov V. V. Podolskii B. A. Aronzon V. V. Rylkov V. P. Lesnikov V. V. Karzanov M. V. Sapozhnikov S. N. Gusev S. A. Levchuk 《Bulletin of the Russian Academy of Sciences: Physics》2010,74(10):1389-1391
The electric, magnetic resonance, and magneto-optical properties of thin laser-plasma deposited 50–100-nm layers of diluted
magnetic semiconductors Ge:(Mn, Al)/GaAs, Ge:(Mn, Al)/Si, and Heusler alloys Co2MnSi/Si, Co2MnSi/GaAs, and Fe2CrSi/GaAs with T
c > 293 K were studied. Anomalous ferromagnetic resonance in Ge:(Mn, Al) layers, ferromagnetism in CoSi/Si characterized by
strong hysteresis in the magneto-optic Kerr effect, and the anomalous Hall effect at 293 K were observed. 相似文献
20.
V. B. Vykhodets T. E. Kurennykh B. V. Slobodin K. V. Trifonov A. Ya. Fishman 《Physics of the Solid State》1997,39(1):35-40
A study is made of the isotope exchange kinetics of tracer oxygen atoms between the gas phase and the CuO1−δ
plane in the YBa2Cu3O7−δ
crystal under isochronous and isothermal annealing. The parameters of the surface energy barrier for oxygen atoms are found.
Fiz. Tverd. Tela (St. Petersburg) 39, 42–48 (January 1997) 相似文献