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1.
考虑电子-声子耦合强度因维度而异,导出了描述三维、二维和一维混晶中电子-声子相互作用的哈密顿量。考虑构成三元混晶的两种二元晶体的晶格失配会使混晶体积随元素组分比改变,在推导三维、二维和一维三元混晶中极化子自陷能量和重整化有效质量时计入了离子相对位移与二元晶体原胞体积的关系。结果表明:磷化物三元混晶中极化子自陷能量和重整化有效质量随元素组分的变化关系呈明显的非线性特征,对晶格适配明显、电子-声子耦合较强的材料,体积效应不可忽略。维度越低,非线性特征和体积效应越明显。 相似文献
2.
R. Eryiğit C. Parlak R. Eryiğit 《The European Physical Journal B - Condensed Matter and Complex Systems》2003,33(3):251-254
We have performed a first-principles study of structural, dynamical, and dielectric properties of the chalcopyrite semiconductor
CuInS2. The calculations have been carried out within the local density functional approximation using norm-conserving pseudopotentials
and a plane-wave basis. Born effective charge tensors, dielectric permitivity tensors, the phonon frequencies at the Brillouin
zone center and mode oscillator strengths are calculated using density functional perturbation theory. The calculated properties
agree with infrared and Raman measurements.
Received 12 December 2002 / Received in final form 17 March 2003 Published online 20 June 2003
RID="a"
ID="a"e-mail: resul@ibu.edu.tr 相似文献
3.
J. Sichelschmidt M. Paraskevopoulos M. Brando R. Wehn D. Ivannikov F. Mayr K. Pucher J. Hemberger A. Pimenov H.-A. Krug von Nidda P. Lunkenheimer V.Yu. Ivanov A.A. Mukhin A.M. Balbashov A. Loidl 《The European Physical Journal B - Condensed Matter and Complex Systems》2001,20(1):7-17
The charge-ordered perovskite Pr0.65Ca0.28Sr0.07MnO3 was investigated by means of magnetic susceptibility, specific heat, dielectric and optical spectroscopy and electron-spin
resonance techniques. Under moderate magnetic fields, the charge order melts yielding colossal magnetoresistance effects with
changes of the resistivity over eleven orders of magnitude. The optical conductivity is studied from audio frequencies far
into the visible spectral regime. Below the phonon modes hopping conductivity is detected. Beyond the phonon modes the optical
conductivity is explained by polaronic excitations out of a bound state. ESR techniques yield detailed informations on the
(H,T ) phase diagram and reveal a broadening of the linewidth which can be modeled in terms of activated polaron hopping.
Received 9 August 2000 相似文献
4.
X. L. Yu S. L. Ban 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,52(4):483-491
The Larsen perturbation method is adopted to study the
influence of magnetic fields on polarons in realistic heterojunctions in a
quasi-two-dimension approximation. The interaction between an electron and
both the bulk longitudinal optical phonons and the two branches of interface
optical phonons is taken into account to show the influence of magnetic
fields at different ranges on the polaron cyclotron mass due to the coupling
of the electron with each branch of phonon modes. The result indicates that
not only do the bulk phonons influence the polaron cyclotron mass, but the
interface phonons do as well. The pressure effect on the cyclotron mass is
also discussed. 相似文献
5.
The ground- and first-excited states of magnetopolarons in two-dimensional quantum dots for all coupling strengths 总被引:2,自引:0,他引:2
B.S. Kandemir T. Altanhan 《The European Physical Journal B - Condensed Matter and Complex Systems》2003,33(2):227-232
The ground- and first-excited state energies of a magnetopolaron in a two dimensional parabolic quantum dot are studied within
a variational calculation for all coupling strength. The Lee-Low-Pines-Huybrecht variational technique that is developed previously
for all coupling strength has been extented for polarons in a magnetic field. The dependence of the polaronic correction on
the magnetic field and the confinement length is investigated. The polarization potential and the renormalized cyclotron masses
as a function of electron-phonon coupling strength and the strength of both confinement potential and magnetic field are also
studied within the same approach.
Received 16 December 2002 / Received in final form 14 April 2003 Published online 4 June 2003
RID="a"
ID="a"e-mail: kandemir@science.ankara.edu.tr 相似文献
6.
B.H. Wu J.C. Cao G.Q. Xia H.C. Liu 《The European Physical Journal B - Condensed Matter and Complex Systems》2003,33(1):9-14
A detailed calculation of interface phonon assisted electron intersubband transition in double GaAs/AlGaAs quantum well structure
is presented. Our calculation concentrates on the lowest two subbands which can be designed to be in resonance with a given
interface phonon mode. Various phonon mode profiles display quasi-symmetric or quasi-antisymmetric shapes. The quasi-antisymmetric
phonon modes give rise to much larger transition rates than those assisted by quasi-symmetric ones. The transition rate reaches
a maximum when the subband separation coincides with a given phonon mode energy. The calculation procedure presented here
can be easily applied to the design and simulation of other low dimensional semiconductor structures, such as quantum cascade
lasers.
Received 22 December 2002 Published online 23 May 2003
RID="a"
ID="a"e-mail: bhwu@263.net 相似文献
7.
Optical vibration modes and electron-phonon interaction in ternary mixed crystals of polar semiconductors 总被引:1,自引:0,他引:1 下载免费PDF全文
Optical vibrations of the lattice and the electron-phonon interaction in polar ternary mixed crystals are studied in the framework of the continuum model of Born and Huang and the random-element-isodisplacement model. A normal-coordinate system to describe the optical vibration in ternary mixed crystals is correctly adopted to derive a new Fr?hlich-like Hamiltonian for the electron-phonon interaction including the unit-cell volume variation influence. The numerical results for the phonon modes, the electron-phonon coupling constants and the polaronic energies for several typical materials are obtained. It is verified that the nonlinearity of the electron-phonon coupling effects with the composition is essential and the unit-cell volume effects cannot be neglected for most ternary mixed crystals. 相似文献
8.
Li Zhang Hong-Jing Xie Chuan-Yu Chen 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,27(4):577-582
Within the framework of the dielectric continuum model, interface optical(IO) and surface optical(SO) phonon modes and the
Fr?hlich electron-IO (SO) phonon interaction Hamiltonian in a multi-shell spherical system were derived and studied. Numerical
calculation on CdS/HgS/H2O and CdS/HgS/CdS/H2O spherical systems have been performed. Results reveal that there are two IO modes and one SO mode for the CdS/HgS/H2O system, one SO mode and four IO modes whose frequencies approach the IO phonon frequencies of the single CdS/HgS heterostructure
with the increasing of the quantum number l for CdS/HgS/CdS/H2O. It also showed that smaller l and SO phonon compared with IO phonon, have more significant contribution to the electron-IO (SO) phonon interaction.
Received 16 October 2001 and Received in final form 23 January 2002 Published online 25 June 2002 相似文献
9.
Sheng-Feng Cheng Guo-Jun Jin 《The European Physical Journal B - Condensed Matter and Complex Systems》2003,32(3):291-296
We investigate coupled optical interface modes in Thue-Morse (TM) dielectric superlattices composed of two kinds of materials
with frequency-dependent dielectric functions. Four basic transfer matrices are derived in the dielectric continuum approximation.
By a standard matrix operation method, the trace map of the global transfer matrix in this configuration is obtained. Under
Born-von Kármán boundary conditions, the frequency spectra are calculated and their branching rules together with the quartet property are elucidated. It is further proved rigorously that nearly all eigenmodes in this framework have extended nature. The quartet of the eigenmodes is illuminated analytically. The common features and pronounced differences compared
with coupled optical interface modes in periodic and Fibonacci dielectric superlattices as well as with other collective elementary
excitations in TM structures are also revealed.
Received 24 September 2002 / Received in final form 11 January 2003 Published online 11 April 2003
RID="a"
ID="a"e-mail: gjin@nju.edu.cn 相似文献
10.
The field-induced carrier redistribution between the subbands of a semiconductor superlattice is treated using the density
matrix approach. The unit cell of the superlattice consists of one quantum well with three occupied subbands. Carrier scattering
on polar-optical phonons is described within the microscopic bulk phonon model. At the tunneling resonance, an intrinsic population
inversion is observed. The temperature dependence of the population inversion is determined.
Received 25 October 2002 / Received in final form 27 November 2002 Published online 6 March 2003
RID="a"
ID="a"e-mail: kl@pdi-berlin.de 相似文献
11.
R.L. Leheny Y.S. Lee G. Shirane R.J. Birgeneau 《The European Physical Journal B - Condensed Matter and Complex Systems》2003,32(3):287-290
Inelastic neutron scattering with high wave-vector resolution has characterized the propagation of transverse spin wave modes
near the antiferromagnetic zone center in the metastable domain state of a random field Ising magnet. A well-defined, long
wavelength excitation is observed despite the absence of long-range magnetic order. Direct comparisons with the spin wave
dispersion in the long-range ordered antiferromagnetic state reveal no measurable effects from the domain structure. This
result recalls analogous behavior in thermally disordered anisotropic spin chains but contrasts sharply with that of the phonon
modes in relaxor ferroelectrics.
Received 2 November 2002 / Received in final form 4 February 2003 Published online 11 April 2003
RID="a"
ID="a"leheny@pha.jhu.edu 相似文献
12.
A combinative method of variational wavefunction and harmonic oscillator operator algebra is used to treat the interface polaron in a semi-infinite polar crystal within parallel electric and magnetic fields perpendicular to the interface. Both the bulk longitudinal optical phonon and the interface optical phonon together with the anisotropic mass of the electron are included. The energy level correction up to the second-order perturbation, cyclotron-resonance frequency and cyclotron mass are expressed as functions of the electric and magnetic fields and a parameter characterizing the mean distance of the polaron from the interface. This theory is used to calculate numerically the single heterostructure AlAs/GaAs, when the electron is at the X high-symmetry point of the conduction band of AlAs. The results show that the magnetic field greatly enhances the polaronic correction of the electron energy levels while the electric field only increases the correction of their surface optical phonon part but obviously decreases that of their bulk optical mode part and thus the total energy correction decreases as the electric field increases. The change of red shift due to the electron-phonon interaction with electric and magnetic fields is also obf ained. 相似文献
13.
M. Georgiev M. Mladenova V. Krastev A. Andreev 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,29(2):273-277
Substitutional impurity ions in crystals are known to displace off-center and to perform hindered rotations around the ideal
lattice positions. The vibronic theory to describe both the off-center displacements and the hindered rotations by a single
angular equation incorporates terms up to 3rd order in the off-center displacement coordinates. When the rotation is confined
to a single plane, the corresponding vibronic equation is equivalent to Mathieu's equation. Extending our earlier work, we
derive here the dipole-dipole coupling to take into account cooperative phenomena. We also derive the optical absorption band
arising from dipolar transitions across “Mexican Hat” surfaces, and we show that hindered rotations gives rise to magnetic
moments quantized in rotational bands.
Received 18 October 2001 / Received in final form 5 March 2002 Published online 2 October 2002
RID="a"
ID="a"e-mail: allxrose@hotmail.com 相似文献
14.
Vl.A. Margulis S.V. Makarov T.V. Piterimova E.A. Gaiduk 《The European Physical Journal B - Condensed Matter and Complex Systems》2003,33(2):153-164
Using a mean-field approximation, we have developed a systematic treatment of collective electronic modes in a semiconductor
superlattice (SL) in the presence of strong electric and magnetic fields parallel to the SL axis. The spectrum of collective
modes with zero wavevector along the SL axis is shown to consist of a principle magnetoplasmon mode and an infinite set of
Bernstein-like modes. For non-zero wavevector along the SL axis, in addition to the cyclotron modes, extra collective modes
are found at the frequencies |Nω
c±Mω
s|, which we call cyclotron-Stark modes (ω
c and ω
s are respectively the cyclotron and Stark frequencies, N and M are integer numbers). The frequencies of the modes propagating in “oblique” direction with respect to the SL axis show oscillatory
behavior as a function of electric field strength. All the modes considered have very weak spatial dispersion and they are
not Landau damped. The specific predictions made for the dispersion relations of the collective excitations should be observable
in resonant Raman scattering experiments.
Received 29 August 2002 / Received in final form 25 February 2003 Published online 4 June 2003
RID="a"
ID="a"e-mail: 612033@inbox.ru 相似文献
15.
U.T. Yakhshiev U.-G. Meißner A. Wirzba 《The European Physical Journal A - Hadrons and Nuclei》2003,16(4):569-574
We investigate the possible modifications of the nucleons' electromagnetic form factors in the framework of a modified Skyrme
model allowing for nucleon deformation and using realistic nuclear mass distributions. We show that such effects are small
in light nuclei
Received: 19 November 2002 / Accepted: 3 December 2002 / Published online: 18 March 2003
RID="a"
ID="a"Address after January 1st, 2003: Helmholtz Institut für Strahlen- und Kernphysik (Theorie), Universit?t Bonn, Nu?allee
14-16, D-53115 Bonn, Germany; e-mail: meissner@itkp.uni-bonn.de
RID="b"
ID="b"Present address: Helmholtz Institut für Strahlen- und Kernphysik (Theorie), Universit?t Bonn, D-53115 Bonn, Germany.
Communicated by V. Vento 相似文献
16.
Interface polarons in a realistic heterojunction potential 总被引:9,自引:0,他引:9
S.L. Ban J.E. Hasbun 《The European Physical Journal B - Condensed Matter and Complex Systems》1999,8(3):453-461
The ground states of interface polarons in a realistic heterojunction potential are investigated by considering the bulk and
the interface optical phonon influence. A self-consistent heterojunction potential is used and an LLP-like method is adopted
to obtain the polaron effect. The numerical computation has been done for the Zn1-xCdxSe/ZnSe system to obtain the polaron ground state energy, self energy and effective mass parallel to the interface. A simplified
coherent potential approximation is developed to obtain the parameters of the ternary mixed crystal and the energy band offset
of the heterojunction. It is found that at small Cd concentration the bulk longitudinal optical phonons give the main contribution
for lower areal electron densities, whereas the interface phonon contribution is dominant for higher areal electron densities.
The interface polaron effect is weaker than the effect obtained by the three dimensional bulk phonon and by the two dimensional
interface phonon models.
Received 17 September 1998 相似文献
17.
We present the ab initio phonon dispersion relations of
-Ga. The calculations are carried out within density functional perturbation theory by using either norm-conserving pseudopotential and 4s and 4p electrons in the valence or ultrasoft pseudopotential and 3d electrons in the valence as well. The inclusion of 3d electrons in the valence turned out to be necessary to better reproduce the experimental frequencies of the stretching modes of the Ga2 dimers present in the
-Ga structure.Received: 29 July 2003, Published online: 19 November 2003PACS:
63.20.Dj Phonon states and bands, normal modes, and phonon dispersion - 71.15.Nc Total energy and cohesive energy calculations - 71.15.Mb Density functional theory, local density approximation, gradient and other corrections 相似文献
18.
B. Eckhardt R. Pandit 《The European Physical Journal B - Condensed Matter and Complex Systems》2003,33(3):373-378
We consider the effects of a shear on velocity fluctuations in a flow. The shear gives rise to a transient amplification that
not only influences the amplitude of perturbations but also their time correlations. We show that, in the presence of white
noise, time correlations of transversal velocity components are exponential and that correlations of the longitudinal components
are exponential with an algebraic prefactor. Cross correlations between transversal and downstream components are strongly
asymmetric and provide a clear indication of non-normal amplification. We suggest experimental tests of our predictions.
Received 26 February 2002 / Received in final form 11 March 2003 Published online 20 June 2003
RID="a"
ID="a"e-mail: bruno.eckhardt@physik.uni-marburg.de
RID="b"
ID="b"Also at: Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore, India 相似文献
19.
M. Camarda G.G.N. Angilella R. Pucci F. Siringo 《The European Physical Journal B - Condensed Matter and Complex Systems》2003,33(3):273-277
The Gaussian Effective Potential in a fixed transverse unitarity gauge is studied for the static three-dimensional U(1) scalar
electrodynamics (Ginzburg-Landau phenomenological theory of superconductivity). In the broken-symmetry phase the mass of the
electromagnetic field (inverse penetration depth) and the mass of the scalar field (inverse correlation length) are both determined
by solution of the coupled variational equations. At variance with previous calculations, the choice of a fixed unitarity
gauge prevents from the occurrence of any unphysical degree of freedom. The theory provides a nice interpolation of the experimental
data when approaching the critical region, where the standard mean-field method is doomed to failure.
Received 18 November 2002 / Received in final form 26 March 2003 Published online 20 June 2003
RID="a"
ID="a"e-mail: giuseppe.angilella@ct.infn.it 相似文献
20.
本文研究多原子极性晶体中表面激子的性质.采用线性组合算符和拉格朗日乘子法,导出强耦合多原子极性晶体中表面激子的有效哈密顿量,得到了强耦合表面激子的重正化质量. 相似文献