共查询到20条相似文献,搜索用时 31 毫秒
1.
Noncentrality of large impurity atoms—Pb and Sn atoms—substituting for Ge atoms in a GeTe lattice has been discovered by means
of EXAFS investigations in Ge0.9Pb0.1Te and Ge0.85Sn0.15Te samples. The transition of impurity atoms into a noncentral position under conditions of a strong local stress is explained
by the participation of an unshared electron pair from the impurity atoms in the formation of the chemical bond.
Pis’ma Zh. éksp. Teor. Fiz. 63, No. 8, 600–603 (25 April 1996) 相似文献
2.
V. I. Al’shits E. V. Darinskaya O. L. Kazakova E. Yu. Mikhina E. A. Petrzhik 《JETP Letters》1996,63(8):668-673
A magnetic induction threshold B
c above which the magnetoplastic effect — depinning of dislocations from paramagnetic pinning centers — can be observed in
samples placed in a magnetic field is predicted and observed in Al, NaCl, and LiF crystals. The existence of a threshold is
associated with the fact that for B<B
c the spin-lattice relaxation time τsl in a dislocation-paramagnetic-center system is less than the time required for spin evolution in a magnetic field resulting
in the removal of the spin forbiddenness of an electronic transition that “switches off” the dislocation-pinning-center interaction.
It is shown that the threshold field B
c is sensitive to temperature and x-ray irradiation of the samples. A new method for measuring the spin-lattice relaxation
time in paramagnetic centers on dislocations is proposed on the basis of the data obtained.
Pis’ma Zh. éksp. Teor. Fiz. 63, No. 8, 628–633 (25 April 1996) 相似文献
3.
D. M. Klyshko 《Journal of Experimental and Theoretical Physics》1997,84(6):1065-1079
The polarization properties of a monochromatic beam of light are ordinarily determined by three numbers, for example, the
Stokes parameters. However, three numbers are no longer sufficient when intensity fluctuations in the polarized modes (or
the correlation between them) are recorded. It is shown that in this case nine parameters, which can be arranged into 3×3
matrices, must be prescribed. The transformation properties of these matrices under polarization converters and the invariants
of the matrices are analyzed. Specifically, the fourth-order polarization P
4 is introduced. Several examples are examined of light with “hidden” polarization—light which is not polarized in the ordinary
sense (P
2=0) but is polarized in fourth order (P
4≠0)—as well as “polarization-squeezed” light in which the quantum fluctuations of the Stokes parameters are suppressed.
Zh. éksp. Teor. Fiz. 111, 1955–1983 (June 1997) 相似文献
4.
A. G. Lipson V. A. Kuznetsov T. S. Ivanova E. I. Saunin S. I. Ushakov 《Technical Physics》1997,42(6):676-682
The variation of the concentration of 14C in graphite subjected to vibratory milling in the presence of heavy (or light) water is investigated using methods of radiocarbon
β-spectral analysis. It is discovered that the C+D2O system exhibits a statistically significant increase in the β counting rate in comparison to the C+H2O system milled under similar conditions. A quantitative model of the transmutation of the 13C isotope into the 14C isotope involving an interaction of multiphonon excitations with deuterons in the graphite crystal lattice in the presence
of background thermal neutrons is proposed.
Zh. Tekh. Fiz. 67, 100–107 (June 1997) 相似文献
5.
V. E. Bisti 《JETP Letters》1999,69(8):584-588
The spectrum of intersubband collective excitations of spin and charge density in a system of quasi-two-dimensional electrons
is calculated in the strong magnetic field limit for filling factors υ≤4. For υ≤2 two new closely spaced modes of collective excitations are obtained. The modes obtained make it possible to give a new
interpretation of the experimentally observed line, which is usually interpreted as being due to single-particle excitations.
Pis’ma Zh. éksp. Teor. Fiz. 69, No. 8, 543–547 (25 April 1999) 相似文献
6.
A. K. Atayan E. M. Kazaryan A. V. Meliksetyan H. A. Sarkisyan 《The European Physical Journal B - Condensed Matter and Complex Systems》2008,63(4):485-492
The absorption of light in an ensemble of non-interacting cylindrical quantum dots in the presence of a magnetic field is
discussed using a model consisting of dots with rectangular infinitely-high potential barriers. The ensemble’s absorption
coefficient is calculated — as well as the threshold frequency of absorption — as a function of the applied magnetic field
and the quantum dot size. Theoretical results are compared with experimental data on magneto-luminescence in an In0.53Ga0.47As/InP cylindrical quantum dot system. In addition, using a perturbation theory framework, the influence of excitonic effects
on the behaviour of the electron-hole energetic spectrum of said system is discussed. 相似文献
7.
O. V. Volkov V. E. Zhitomirskii I. V. Kukushkin K. von Klitzing K. Eberl 《JETP Letters》1997,66(8):575-580
The radiative recombination spectra of two-dimensional electrons with free photoexcited holes are investigated for a wide
variety of GaAs/ AlGaAs quantum wells, with different thicknesses and electron densities. It is found that for certain, close
to integral, filling factors an intense line corresponding to an Auger process — radiative recombination with the emission
of an additional magnetoplasmon — appears in the luminescence spectrum. The new line is shifted to lower energies with respect
to the zero Landau level, and the magnetic field dependence of the energy splitting between these lines agrees with the theoretical
concepts of the dispersion of magnetoplasmon excitations. This makes it possible to estimate the magnetoplasmon energy at
the roton minimum.
Pis’ma Zh. éksp. Teor. Fiz. 66, No. 8, 539–544 (25 October 1997) 相似文献
8.
V. I. Gavrilenko I. V. Erofeeva A. L. Korotkov Z. F. Krasil’nik O. A. Kuznetsov M. D. Moldavskaya V. V. Nikonorov L. V. Paramonov 《JETP Letters》1997,65(2):209-214
The impurity photoconductivity spectra of Ge/Ge1−x
Six strained heterostructures with quantum wells are investigated. It is established that the built-in deformation in quantum-size
Ge layers substantially changes the spectrum of shallow acceptors, shifting it into the long-wavelength region of the far-IR
range. In strong magnetic fields the photoconductivity lines are observed to split and shift as a function of the field. This
makes it possible to carry out a classification of the transitions.
Pis’ma Zh. éksp. Teor. Fiz. 65, No. 2, 194–198 (25 January 1997) 相似文献
9.
E. D. Eidel'man 《Physics of the Solid State》1999,41(1):148-152
The possibilities for excitation of electromagnetic field structures and convection cells, i.e., temperature and velocity
structures, in a thermotropic cholesteric liquid crystal in the presence of flow are studied. Estimates are made and possible
experiments for observing such structures are discussed. A special thermoelectric effect is investigated as the cause of these
excitations — the influence of a heating-induced change in the pitch of the cholesteric helix of the molecules on the permittivity
and the electric conductivity of the material.
Fiz. Tverd. Tela (St. Petersburg) 41, 165–170 (January 1999) 相似文献
10.
A. V. Chernenko N. G. Kalugin O. A. Kusnetsov 《Journal of Experimental and Theoretical Physics》1998,87(2):337-341
This paper reports on the first investigation made of luminescence of Ge/Ge1−x
Six heterostructures at liquid-helium temperatures in a magnetic field of up to 14 T. The luminescence lines observed in the
spectra are due to both free and impurity bound excitons in Ge layers. The diamagnetic shift of the quasi-two-dimensional
exciton has been measured. From the experimental data the size of the exciton has been estimated to be 75–90 Å.
Zh. éksp. Teor. Fiz. 114, 619–627 (August 1998) 相似文献
11.
The three-band Hubbard model — both pure and with static non-magnetic impurities — has been studied within a self-consistent
numerical Hartree-Fock (HF) scheme. The system shows nesting properties only in the absence of direct O-O hopping. Spin excitations
in the system are gapless with the existence of a Goldstone mode in the broken-symmetry state. The variation of spinwave velocity
with Cu-site Coulomb repulsion shows a (1/(2U
d)+(1/Δ)) dependence in the strong-coupling limit. Each non-magnetic impurity in the system gives rise to two gap states for
a particular spin and the local moment produced is robust even at finite concentration of mobile hole doping. The gapless
Goldstone mode is preserved even in case of unequal concentration of impurities on the two sublattices. 相似文献
12.
The effective nonunidirectional energy exchange between like-polarized light beams is investigated experimentally on a photorefractive
grating formed by diffusion drift in a bismuth silicate crystal placed in an alternating external electric field.
Fiz. Tverd. Tela (St. Petersburg) 41, 632–637 (April 1999) 相似文献
13.
M. V. Sazhin 《Journal of Experimental and Theoretical Physics》1998,86(2):220-225
The structure of the electromagnetic field inside a laser cavity—a gravitational-wave detector—is studied. The properties
of the spatial and temporal phases of the standing electromagnetic wave are discussed in detail and the corrections appearing
in the electric field of the wave as a result of the action of gravitational radiation on the optical system are determined.
Zh. éksp. Teor. Fiz. 113, 398–408 (February 1998) 相似文献
14.
The possibility of resonance during elastic intravalley scattering in n-type semiconductors is investigated in connection with the crossing (due to anisotropy of the effective mass) of the energy
levels of excited states of a shallow donor as functions of the magnetic field. The hybridization of states of different frequencies
in the vicinity of a crossing is attributed to the emergence of a nonzero dipole moment of the excited impurity atom and,
accordingly, a long-range potential, which creates carrier-transport anomalies. The lower part of the donor spectrum is calculated
as a function of the magnetic field in Si with B∥〈001〉 and in Ge with B∥〈111〉 or B∥〈110〉. A crossing occurs in Ge in the field range 9.9 T<B<16.7 T and in Si in the field range 10.5 T<B<37.7 T. The characteristic longitudinal relaxation time and the transverse conductivity, which are determined by scattering
at excited donors in the presence of the hybridization of states, are calculated.
Zh. éksp. Teor. Fiz. 112, 975–1010 (September 1997) 相似文献
15.
A study is made of the temperature and field dependences of the anisotropic magnetization of a quasi-one-dimensional charge-density-wave
conductor — the blue bronze K0.3 MoO3. Nonlinearity of the magnetization curves is observed at temperatures below 100 K. The temperature and field dependences
of the magnetic moment show the effect to be of a collective nature.
Pis’ma Zh. éksp. Teor. Fiz. 68, No. 4, 281–286 (25 August 1998) 相似文献
16.
A. V. Bazhenov A. V. Gorbunov M. Yu. Maksimuk T. N. Fursova 《Journal of Experimental and Theoretical Physics》1997,85(1):135-140
Spectra of photoinduced light absorption in C60 films at high and low excitations in the temperature range between 15 and 300 K have been measured. In addition to the well-known
explanation of photoinduced absorption in terms of optical transitions in the system of photogenerated singlet excitons, triplet
excitons, and polarons, changes in the absorption spectrum of the fullerite ground state must be considered. We suggest taking
into account the effect of crystal field in explaining the features of the photoinduced absorption spectrum. A feature similar
to the inverted luminescence spectrum and ascribed to optical excitation of singlet excitons, which is partially allowed owing
to intermolecular interaction, has been detected in spectrum of photoinduced absorption.
Zh. éksp. Teor. Fiz. 112, 246–256 (July 1997) 相似文献
17.
M. N. Khlopkin 《JETP Letters》1999,69(1):26-30
The specific heat of a V3Si single crystal (T
c=17 K, H
c2=20 T) in magnetic fields up to 8 T isinvestigated experimentally for three orientations of the field relative to the crystallographic
directions — H∥〈001〉, H∥〈110〉, and H∥〈111〉. Both the upper critical magnetic field and the specific heat of the mixed state are observed to depend on the orientation
of the magnetic field relative to the crystallographic directions (anisotropy): The critical field reaches its maximum value
and the specific heat its minimum value in a field along the 〈001〉 direction. The anisotropy scale in both phenomena increases
as the magnetic field and reaches 3% in a 6 T field. The interrelationship of the upper critical field anisotropy and the
specific-heat anisotropy in type-II superconductors is studied. It is shown that the anisotropy of the specific heat in the
mixed state in weak fields can serve as a criterion for nontrivial pairing.
Pis’ma Zh. éksp. Teor. Fiz. 69, No. 1, 26–29 (10 January 1999) 相似文献
18.
G. A. Petrakovskii A. M. Vorotynov H. Szymczak L. Gladczuk 《Physics of the Solid State》1998,40(9):1520-1522
The temperature dependence of the longitudinal magnetostriction of a CuGeO3 single crystal is measured within the temperature range 4.2–20 K in a magnetic field of 10 T. As the temperature is raised
above 4.2 K, the magnetostriction at first increases from vanishingly small values, attains a maximum at a temperature of
approximately 12 K, and then abruptly drops as the temperature approaches the spin-Peierls transition. The results are interpreted
on the basis of a simple model utilizing the real pattern of magnetic excitations in the spin system.
Fiz. Tverd. Tela (St. Petersburg) 40, 1671–1673 (September 1998) 相似文献
19.
A. V. Tyunis V. A. Shaburov Yu. P. Smirnov A. E. Sovestnov 《Physics of the Solid State》1997,39(9):1337-1340
The electronic structure of U and Ge in the solid solutions U(Al1−x
Gex)3 is investigated by measuring x-ray line shifts. It is shown that uranium has the mixed valence U3+ [Rn](5f
3)-U4+ [Rn](5f
2) over the entire composition range (0⩽x⩽1) and that the population of the uranium 5f shell increases by ∼0.28 5f electrons/U atom from UAl3 (x=0) to UGe3 (x=1). The electronic structure of Ge is close to the electronic structure of Ge metal over the entire composition range 0<x⩽1. No variation of the population of the Ge 4p shell is detected to within the experimental error (∼0.1 4p electrons/Ge atom) as the composition varies from x=0.2 to 1. It is established that the delocalization of a U 5f electron occurs as a result of its transition to the s or d band of the same uranium atom.
Fiz. Tverd. Tela (St. Petersburg) 39, 1505–1508 (September 1997) 相似文献
20.
Two metastable states of a multilayer Ge/p-Ge1−x
Six heterosystem with wide (∼ 35 nm) potential wells (Ge) are observed in strong magnetic fields B at low temperatures. In the first state, the Hall resistivity exhibits an inflection near the value ρxy=h/e
2 scaled to one Ge layer. The longitudinal magnetoresistivity ρxx(B) possesses a minimum in the range of fields where this inflection occurs. The temperature evolution of the inflection in
ρxy(B), the minimum of ρ xx(B), and the value of ρxy at the inflection indicates a weakly expressed state of the quantum Hall effect with a uniform current distribution over
the layers. In the second metastable state, an unusually wide plateau near h/2e
2 with a very weak field dependence is observed in ρxy(B). Estimates show that in these samples the Fermi level lies below but close to the top of the inflection in the bottom of
the well. For this reason, the second state can be explained by separation of a hole gas in the Ge layers into two sublayers,
and the saturation of ρxy(B) near h/2e
2 can be explained by the formation of a quantum Hall insulator state.
Pis’ma Zh. éksp. Teor. Fiz. 70, No. 4, 290–297 (25 August 1999) 相似文献