摘要
使用正则变换方法,考察了一维Holste in极化子能带和有效质量的温度依赖性。结果表明,对于一定的电子声子耦合强度,Holste in极化子能带宽度随温度升高而变窄,有效质量随温度升高而增大。特别是当电子声子耦合强度足够大时,极化子能带宽度在很小的温度范围内会迅速地变为零,我们认为这种情况实际上是极化子从能带状态向自陷局域态的迅速转变,这与通常的相变现象有点相类似。当电子声子耦合常数越大时,极化子有效质量随温度的升高而增加得越快。很显然,研究电子声子相互作用,对理解固体的光学和输运等性质将有重要的意义。
As ones know, the polaron is a quasiparticle formed by an electron and phonons. Due to Coulomb interaction, the electron will make the lattice deformation take place, meanwhile, the deformation potential induced by the lattice deformation will exert on the electron, the electron-phonon ：interaction influence doubtless on the state of motion of an electron, for example, the energy band and effective mass of an electron could change by the interaction, the electron can also be trapped by the deformable lattice, therefore, the research on the polaron is very important in understanding optical and transport properties of a solid.
Studying electron-phonon interaction has been a main subject in condensed matter physics; in experiments, the influences of the temperature on the forbidden-band width of semiconductors have been observed very early, with the increase of the temperature, the forbidden-band width of most semiconductors will narrow,but a few will widen, these situations are closely relevant to the electron-phonon interaction. In particular, recently, a large amount of experimental results, ranging from infrared spectroscopy to transport properties involving the colossal magnetoresistance and high-Tc superconductivity, has pointed out the importance of the electron-phonon interaction, which has renewed the interest in studying the models of the electron-phonon coupled system, especially, the Holstein polaron, for its relative simplicity, is the most considered model for the interaction of a single tight-binding electron coupled to phonons.
In the past several decades, the Holstein poloron has been studied in detail in one-dimensional lattices, various theoretical methods, such as variational approaches, the Global-Local variational method, the coherent-state expansion method, have been developed to study features of the Holstein polaron including ground-state energy, polaron energy band, effective mass and so on. However, so far, the work considering the influences of the temperature on features of the Hols
出处
《发光学报》
EI
CAS
CSCD
北大核心
2006年第4期447-451,共5页
Chinese Journal of Luminescence
基金
湖南省教育厅资助项目(2006)
