磁场中准二维强耦合磁极化子的有效质量

Effective Mass of Quasi-two-dimensional Strong-coupling Magnetopolaron in Magnetic Fields

采用改进的线性组合算符和LLP变分法,研究了外磁场对量子阱中电子与界面光学声子强耦合、与体纵光学声子弱耦合磁极化子的有效质量的影响。对AgCl/KI量子阱进行了数值计算,结果表明,磁极化子的有效质量随阱宽的增加而减小,随磁场的增强而增大,但不同支声子与电子和磁场相互作用对磁极化子有效质量的贡献大不相同。

The ground state of the magnetopolaron, which is weakly coupled with the bulk longitudinal optical phonons and strongly coupled with the interface optical phonons, in an infinite quantum well within a magnetic fields are studied by using Tokuda＇ linear-combination operator and the modified Lee-Low-Pines variational method. The law of the change of the effective mass of the magnetopolaron changing with the quantum well＇s width and the magnetic fields are obtained. Numerical calculations, taking the AgCl/KI quantum well as an example, are performed. The results show that as the following： 1. The effective mass of the magnetopolaron in the quantum well is composed of two parts ： the first part is the effective mass of the magnetopolaron induced by the interaction between the electron and the longitudinal optical phonon, the second part is the contribution of the interaction between the electron and the interface optical phonons and the magnetic fields. We have found that, among the four branches of the interface optical phonons, only the interaction between the electron and two branches of the interface optical phonons with frequency of ω ＋ ＋ and to ω - ＋ , the magnetic fields has the contribution to the effective mass of the magnetopolaron also, but other two branches of the interface optical phonons with frequency of ω ＋ - and ω - - have not any contribution to the effective mass of the magnetopolaron. 2. The total effective mass of the magnetopolaron will decrease drasticlly with increasing the well＇s width, at last, it will tend to the limiting value of the bulk case slowly. This shows that, when the well＇s width is smaller, the contribution to the effective mass of the magnetopolaron by the interaction between the electron and the interface optical phonons is important, on the contrary, the contribution to the effective mass of the magnetopolaron by the interaction between the electron and the longitudinal optical phonon increases with increasing the well＇s width, and becomes the dominant. 3. The effective mass of the magnetopolaron will increases with increasing the magnetic field. It is indicated that the magnetic fields will intensify the interaction between the electron and phonons, and will influence on the interaction between the electron and the interface optical phonons only, but has nothing with the interaction between the electron and the longitudinal optical phonon.