磁场对非对称量子点中极化子性质的影响

Influence of Magnetic Field on Properties of Polaron in an Asymmetry Quantum Dot

采用线性组合算符和幺正变换方法研究磁场对非对称量子点中弱耦合磁极化子性质的影响。导出了非对称量子点中弱耦合磁极化子的振动频率、基态能量和基态结合能随量子点的横向和纵向有效受限长度、磁场和电子-声子耦合强度的变化关系。数值计算结果表明:非对称量子点中弱耦合磁极化子的基态能量和基态结合能随量子点的横向和纵向有效受限长度的增加而迅速增大。随回旋频率的增加而增大,随电子-声子耦合强度的增加而减小。

With the further development of material production technology low dimensional electronic systems, quantum dot, quantum well and quantum wire et al, have been produced with molecular beam epitaxy tech- nigne（MBE）, metal organic chemical vapor deposition （MOCVO） and chemical self-assemble technique. Due to the small structures of quantum dot some physical properties such as optical and electron transport characteristics are quite different from those of the bulk materials, especially. The properties of the electrons in the quantum dots play a more important role in electronic and optical properties of polar crystalline materials. There has been great interest in investigation quantum dots both theoretically and experimentally. Many investigators studied the properties of the polaron in an asymmetry quantum dots in many aspects by a variety of theore-tical and experimental methods. Recently, the properties of strong-and-weak-coupling polaron in an asymmetry quantum dot have been studied using the linear-combination operator and unitary transformation method by the present authors. However, using linear-combination operator method, the properties of the polaron in an asymmetry quantum dot has not been fully investigated so far. The purpose of this present paper is to explore the effect of the longitudinal and transverse effective confinement length of quantum dot, electronphonon coupling strength and the cyclotron frequency of magnetic field on the properties of weak-coupling mag- netoplaron in an asymmetry quantum dots. We obtain an expression for the ground state energy and the state binding energy of the weak-coupling magnetopolaron ground in an asymmetry quantum dot as a function of the longitudinal and transverse effective confinement length, the electron-phonon coupling strength and cyclotron frequency of magnetic field by using a linear combination operator and unitary transformation method. Numerical calculations are performed and the results show that the ground state energy and ground state binding ener- gy of the weak-coupling magnetopolaron in an asymmetry quantum dot will increase strongly with decreasing the transverse and longitudinal effective confinement length of quantum dot, and will increase with increasing the cyclotron frequency of magnetic field and decreasing the electron-phonon coupling strength.