半导体超晶格系统中的磁电调控电子自旋输运研究

通过采用转移矩阵方法求解自旋电子隧穿过程，理论研究了半导体超晶格系统中电子自旋输运的磁电调控行为.结果表明：仅对超晶格系统施以磁调制，隧穿系数将出现自旋分裂，随磁场增强，电导自旋极化率变大且展宽于费米能区；若选取不变磁场情况，同时施以间隔周期电场调制，超晶格的电子极化率将有更为显著地提高.进一步发现，随电场强度的改变，电子自旋输运行为显然存在两个明显不同区域，下自旋电子将在不同调制区域表现为不同的变化趋势.然而，若对周期磁超晶格施加间隔两周期的电调制，自旋电导输运的临界行为消失，电导极化率在高能区的共振峰 关键词： 半导体超晶格 自旋输运 磁电调控

Magnetic-electric controllable spin transport in semiconductors superlattic

By solving electron tunneling problem in semiconductor superlattice, the magnetic-electric controllable spin transport is theoretically investigated.The results show that, with magnetic modulation only,the spin transmission will separate, and with the magnetic filed increasing,the conductance polarization is enhanced and its peaks are widened. By both magnetic and single interval electric barrier modulation,the conductance polarization will be evidently improved; and at the same time,there are two distinct transport regions for different electric modulation, in which the down-spin electron obeys different change rules with different electric filed.However,applying electric modulation at intervals of two periods on the magnetic superlattic,it is noticed that the critical behavior of electron spin transport disappears,and the resonant peak of the conductance polarization also degenerates in the high energy region.These results show that the symmetry is an important factor for spin transport in the semiconductor superlattice.