无序杂质、磁场对“三明治”式二维系统电导的影响

Influence of disorder and magnetic field on conductance of “sandwich” type two dimensional system

为研究二维电子系统中电子输运的问题及在磁场作用下二维无序杂质系统电导的物理性质,通过运用格林函数以及散射矩阵理论的方法,在格点模型的基础上,对"三明治"式二维电子系统电导的量子化现象进行了分析。导线与散射体的接触减小了系统的电导,削减了电导量子台阶现象,使得系统的电导随着导线与介质间耦合的变小而降低;当系统受到外磁场作用时,系统电导的变化随着磁场的变化表现出周期性震荡行为,这种震荡变化的剧烈程度与电子的能量有关;受杂质散射的影响,系统电导随无序杂质浓度的增大而减小,在某些特殊掺杂的浓度下,对于一些特殊的电子能量,系统的电导可以达到理想情况下的阶梯值。研究成果对于"三明治"式二维电子系统电导的进一步研究具有借鉴意义。

In order to discuss the transport phenomena and the physical properties of the doping of the disorder system under magnetic field,the electron transport in a two-dimensional system is studied by using Green function and scattering matrix theory.Base on the two-dimensional lattice model,the phenomenon of quantized conductance of the ＂sandwich＂ type electronic system is analyzed.The contact between the lead and the scatterer reduce the system＇s conductance,and whittle down the quantum conductance stair-stepping phenomenon;when an external magnetic field acts on to the system,the conductance presents a periodicity oscillation with the magnetic field.The intensity of this oscillation is related to the energy of the electron;with the increase of the impurity concentration,the conductance decreases.In some special doping concentration,the conductance of the system can reach the ideal step value corresponding to some special electron energy.The result could provide reference for further study of the conductance of the ＂sandwich＂ type two dimensional system.