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1.
XIEWen-Fang 《理论物理通讯》2001,35(4):497-500
We investigate the effect of the position of the donor in quantum dots on the energy spectrum in the presence of a perpendicular magnetic field by using the method of few-body physics,As a function of the magnetic field,we find,when D^- centers are placed sufficiently off-center,discontinuous ground-state transitions which are similar to those found in many-electron parabolic quantum dots.Series of magic numbers of angular momentum which minimize the ground-state electron-electron interaction energy have been discovered.The dependence of the binding energy of the gound-state of the D^- center on the dot radius for a few values of the magnetic field strength is obtained and compared with other results. 相似文献
2.
This paper presents a systematic study of the ground-state binding energies of a hydrogenic impurity in quantum dots subjected to external electric and magnetic fields.The quantum dot is modeled by superposing a lateral parabolic potential,a Gaussian potential and the energies are calculated via the finite-difference method within the effectivemass approximation.The variation of the binding energy with the lateral confinement,external field,position of the impurity,and quantum-size is studied in detail.All these factors lead to complicated binding energies of the donor,and the following results are found:(1) the binding energies of the donor increase with the increasing magnetic strength and lateral confinement,and reduce with the increasing electric strength and the dot size;(2) there is a maximum value of the binding energies as the impurity placed in different positions along the z direction;(3) the electric field destroys the symmetric behaviour of the donor binding energies as the position of the impurity. 相似文献
3.
In this paper, an exciton trapped by a Gaussian confining potential quantum
dot has been investigated. Calculations are made by using the method of
numerical diagonalization of Hamiltonian in the effective-mass
approximation. The dependences of binding energies of the ground state and
the first excited state on the size of the confining potential and the
strength of the magnetic field are analysed explicitly. 相似文献
4.
XIE Wen-Fang 《理论物理通讯》2008,49(2):507-510
The properties of the low-lying states of a negative donor center trapped by
a spherical quantum dot, which is subjected to a parabolic potential
confinement, are investigated in the absence of magnetic field. The
calculations have been performed by means of the exact diagonalization of
the Hamiltonian matrix within the effective-mass approximation. We find that there is only one bound state the D- center in a spherical parabolic quantum dot in the absence of magnetic field. The binding energy of the ground state is obtained as a function of the dot size. Moreover, the critical confined potential radius value at which the negative donor center changes from unbound to bound is obtained. 相似文献
5.
6.
The magnetoexciton binding energy dependency on aluminium concentration in cylindrical quantum wires
A calculation of the binding energy of an exciton confined in cylindrical quantum wires of GaAs surrounded by (Ga, Al) As in the presence of a uniform magnetic field is reported as a function of wire radius, potential height and magnetic field strength, using effective mass approximation and variational approach techniques. For larger magnetic field strength and aluminium (Al) concentration values, the binding energies get larger as expected and are found to be in good agreement with previous theoretical reports. However, we also observed a shift in the binding energy maxima position to smaller wire radii with increasing magnetic field strength and Al concentration. 相似文献
7.
本文在有效质量近似下,通过自洽地求解薛定鄂方程及泊松方程计算了在温度T=273 K,磁感应强度B=25 T,Si均匀掺杂的GaAs/AlGaAs量子阱系统的电子态结构.研究了温度与外磁场对子带能量,本征包络函数,自洽势,电子密度分布,及费米能量的影响.发现在给定磁感应强度B=fi0下,随温度升高子带能量单调增加,费米能量单调递减,自洽势的势阱变深变陡,电子密度分布变宽,峰值降低;在给定温度下,随磁感应强度的增加子带能量及费米能量单调递增,自洽势阱变浅变宽,电子密度分布变窄,峰值升高. 相似文献
8.
Binding energy of the donor impurities in GaAs-Ga_(1-x)Al_xAs quantum well wires with Morse potential in the presence of electric and magnetic fields
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The behavior of a donor in the GaAs–Ga_(1-x)Al_xAs quantum well wire represented by the Morse potential is examined within the framework of the effective-mass approximation. The donor binding energies are numerically calculated for with and without the electric and magnetic fields in order to show their influence on the binding energies. Moreover, how the donor binding energies change for the constant potential parameters(De, re, and a) as well as with the different values of the electric and magnetic field strengths is determined. It is found that the donor binding energy is highly dependent on the external electric and magnetic fields as well as parameters of the Morse potential. 相似文献
9.
《Superlattices and Microstructures》2001,29(5):319-328
Using a variational procedure within the effective-mass approximation we have calculated the binding energies of shallow-donor impurities in cylindrical GaAs quantum-well wires, in an axial magnetic field and an infinite confinement potential. In contrast to the previous results in quantum wells, we have found that, in the magnetic field, the impurity binding energy may be increased or decreased as a function of the impurity location in the quantum wire. On the basis of analysis of the variation of the binding energy with magnetic field strength, a method is proposed for experimentalists to confirm the presence of a shallow donor in the vicinity of the wire boundary. 相似文献
10.
The ground-state and lowest excited-state binding energies of ahydrogenic impurity in GaAs parabolic quantum-well wires (QWWs)subjected to external electric and magnetic fields are investigated using the finite-difference method within the quasi-one-dimensional effective potential model. We define an effective radius ρeff of a cylindrical QWW, which can describe the strength of the lateral confinement. For the ground state, theposition of the largest probability density of electron in x-y plane is located at a point, while for the lowest excited state, is located on a circularity whose radius is ρeff. The point and circularity are pushed along the left half of the center axis of the quantum-well wire by the electric field directed along theright half. When an impurity is located at the point or within the circularity, the ground-state or lowest excited-state binding energies are the largest; when the impurity is apart from the point or circularity, the ground-state or lowest excited-state binding energies start to decrease. 相似文献
11.
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
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13.
Magnetic rotation and antimagnetic rotation are exotic rotational phenomena observed in weakly deformed or near-spherical nuclei, which are respectively interpreted in terms of the shears mechanism and two shearslike mechanism. Since their observations, magnetic rotation and antimagnetic rotation phenomena have been mainly investigated in the framework of tilted axis cranking based on the pairing plus quadrupole model. For the last decades, the covariant density functional theory and its extension have been proved to be successful in describing series of nuclear ground-states and excited states properties, including the binding energies, radii, single-particle spectra, resonance states, halo phenomena, magnetic moments, magnetic rotation, low-lying excitations, shape phase transitions, collective rotation and vibrations, etc. This review will mainly focus on the tilted axis cranking covariant density functional theory and its application for the magnetic rotation and antimagnetic rotation phenomena. 相似文献
14.
双阱光学超晶格中的超冷原子是近期冷原子物理领域的研究热点. 本文推广提出了实现三阱光学超晶格的方案, 并采用精确对角化的方法分别研究了弱磁场下对称三阱 光学超晶格中铁磁性和反铁磁性的自旋为1的原子系统的基态, 发现二者的相图很不相同: 反铁磁性原子对应的相图中没有沿磁场方向总自旋磁量子数为±2的基态, 而铁磁性原子对应的相图中可能有. 在负的二次塞曼能量区域, 铁磁性原子的相图中只有完全极化态. 分析了可控参数影响基态的物理本质. 由于这些量子自旋态可以通过调节外磁场和光势垒的高度非常简便而精确地控制, 适合用来研究自旋纠缠.
关键词:
三阱光学超晶格
自旋为1的原子
弱磁场 相似文献
15.
Wenfang Xie 《Solid State Communications》2003,127(5):401-405
Two interacting electrons in a Gaussian confining potential quantum dot are considered under the influence of a perpendicular homogeneous magnetic field. The energy levels of the low-lying states are calculated as a function of magnetic field. Calculations are made by using the method of few-body physics within the effective-mass approximation. A ground state behavior (singlet→triplet state transitions) as a function of the strength of a magnetic field has been found in the weak confinement case as a two-electron quantum dot with parabolic confining potential. 相似文献
16.
D. Kolb W. -D. Sepp B. Fricke T. Morović 《Zeitschrift für Physik A Hadrons and Nuclei》1978,286(2):169-171
The modification of the two center screened electronic Coulomb potential due to relativistic kinematical effects is investigated in the Coulomb gauge. Both nuclear and electronic charges were approximated by Gaussian distributions. For ion velocitiesv/c =0.1 the effect may roughly be approximated by a 0.1 % increase in the effective strength for the monopole term of the two center potential. Thus for ion kinetic energies not exceeding a few MeV/nucleon this relativistic contribution induces small effects on the binding energy of the 1σ-electrons except for super critical charges. 相似文献
17.
In this work, using the effective mass approximation within variational approach, we have studied the behavior of the excitonic binding energies in a cylindrical quantum wire with a parabolic confinement under the effect of externally applied magnetic field. We have shown that the excitonic binding energy is sensitive to the magnetic field value in contrast to the other potential profiles studied in literature such as rectangular quantum wells (wires). 相似文献
18.
The method of few-body physics is applied to treat a D-<\sup> center quantum dot system in a magnetic field. The magnetic field is applied in the z direction. Using this method, we investigate the energy spectra of low-lying states of D-<\sup> center quantum dots as a function of magnetic field. The dependence of the binding energies of the ground-state of the D-<\sup> center are calculated as a function of the dot radius with a few values of the magnetic field strength and compared with other results. 相似文献
19.
The ground state energies of an exciton in a GaAs/Ga1-xAlxAs quantum well structure for perpendicular magnetic field of arbitrary strength are studied. The results show that the energy of the magneto exciton will be increased with the increase of quantum well width and magnetic field strength. 相似文献
20.
势阱中的类氢杂质的能级问题一直为学术界所长期关注。讨论了异质界面上中性施主D0和负施主离子D-的能量随垂直于界面的磁场的变化情况,同时将磁场和势阱结合起来考虑其对类氢杂质的影响。研究发现随磁场的增大,其对D0基态能的影响越来越大,对其束缚能的影响逐渐变小,而对D-中心,磁场的作用使得D-由非束缚态转变为束缚态。计算中分别选取了两种不同的波函数,分析了这两种波函数的适用范围,利用变分的方法得到此结构中D0中心的基态能量和束缚能与D-中心角动量L=-1自旋三重态的本征能量和束缚能随磁场的变化关系,找到了此三重态由非束缚态转变到束缚态对应磁场的阈值。 相似文献