阶梯型量子线中电子自旋极化输运性质的研究

Research on transport properties in stair quantum wire

采用递归格林函数法研究了含Rashba自旋轨道耦合效应的阶梯型量子线中电子自旋极化输运性质.结果表明由于多阶梯结构量子线的纵向不对称性和Rashba自旋轨道耦合效应产生的势阱导致系统中出现了准束缚态,它与连续态耦合,从而使系统电导出现了Fano共振结构.进一步研究发现,随着共振腔长度的增加,系统电导的共振峰数目会增加,幅度也会增强.与单阶结构相比,多阶结构的极化电流更大,并且在特定能量区间出现了若干条禁带.这些效应说明所研究的体系有可能能用来设计自旋电子器件.

By using the spin-resolved lattice Green function method, this paper theoretically studies the transport properties of spin-polarized electron in stair quantum wire with the presence of Roshba spin-orbit coupling （SOC）. The results of the study reveal that because of the interfering of the conductance states and bound states, Fano resonances exist in that particular system, which is in consequence of the lengthwise asymmetry of multi-stair structure and potential well generated from the Rashba SOC effect. Furthermore, when the length of the resonant cavity increases, there are more and keener resonance peaks. In addition, the multistair quantum wire has stronger polarized current, compared with the single -stair. Interestingly, the conductance of the system has some forbidden gaps in a certain energy range. Those results may provide another effective way to design a spin filter device in the future.