抛物量子点中弱耦合磁极化子的振动频率和相互作用能

采用改进的线性组合算符和幺正变换方法研究磁场中抛物量子点弱耦合磁极化子的性质,导出抛物量子点中磁极化子的振动频率和相互作用能与磁场、受限强度和电子声子耦合强度的关系.对GaAs晶体进行数值计算,结果表明,量子点受限强度越大,量子点弱耦合磁极化子的振动频率和相互作用能越大.

Vibration Frequency and Interaction Energy of Weak Coupling Magnetoplaron in Parabolic Quantum Dot

Recently,with the quick development of techniques to fabricate material,the physical characteristic of low dimensional material have aroused great interest.The properties of magnetopolaron in quantum dot has been studied by many theoretical and experimental method by many investigators.Zhu and Gu theoretically studied the effect of electric-fields on shallow donor impurities state in a harmonic quantum dot by using effective mass approximation method.The interaction of electrons,confined in a quasi-zerodimensional quantum dot and longitudinal-optical(LO)phonons,placed in a perpendicular magnetic field,was studied by Wendler,et al.within second-order perturbation theory.Magnetic field effects on strong-coupling polarons in a parabolic quantum dot were investigated by Zhu et al.with the Landau-Pekar variational treatment.Zhau and Gu calculated the ground state and the first excited state of the strong-coupling magnetopolaron in a cylinder-shaped quantum dot by using the variational method of Pekar type.Using a very simple trial function with only one variational parameter,the effects of the parabolic confining potentials and magnetic fields on the binding energy of hydrogen impurities in quantum dots were studied indetail by Nguyen et al.By using the method of few-body physics,Xie investigated the binding energy of the ground state of the D^- centers in quantum dots in magnetic field.Chen et al.investigated the thickness effect on the shallow donor impurity-bound polaronic energy levels in parabolic quantum dot in magnetic fields by means of the Larsen method.However,the properties of the polaron and the magnetopolaron in quantum dot has not been investigated by a linear combination operator method so far.The ground state binding energy and the mean number of optical phonons in the cloud around electron of the polaron and the magnetopolaron in parabolic quantum dot were calculated by the method of a linear-combination operator by the present authors.The purpose of this present paper is to explore the effect of the magnetic field B,the electron-phonon coupling strength α,the confinement strength ω₀ and the variational parameter p₀ on the properties of the weak coupling magnetopolaron in parabolic quantum dot.The relation between the vibration frequency λ and the interaction energy H_int of the magnetoploaron in parabolic quantum dot with the magnetic field,the confinement strength and the electron-phonon coupling strength were derived by using an improved linear combination operator method.Numerical calculations for GaAs crystal show that the vibration frequency λ and the interaction energy H_int of the weak coupling magnetopolaron in parabolic quantum dot will increase with increasing the confinement stregth ω₀,the vibration frequency λ will increase with decreasing the variational parameter and the cyclotron frequency,whereas H_int increases with increase of p₀,and H_int increases with decrease of ω_c.