单晶二维材料势垒层磁性隧道结的偏压效应

The effect of bias voltage on the magnetic tunnel junction with single crystal 2D-material barrier

基于Bethe理论和双束近似方法,构建了适用于单晶势垒层磁性隧道结的理论模型。该理论模型将单晶势垒层视作周期性光栅,因而可以充分地计入隧穿电子的相干性。进一步地,利用该理论计算了以单晶二维材料作为势垒层的磁性隧道结的偏压效应。根据计算结果,讨论了铁磁电极对偏压效应的影响以及偏压对厚度效应的影响。研究表明,由于单晶周期性势垒对隧穿电子散射导致透射电子波具有相干性,隧穿电导和TMR将随偏压振荡,且振荡的周期随铁磁电极半交换劈裂能的增大而增大。此外,研究结果还发现,当偏压低于100 mV时,偏压对隧穿磁阻效应的影响很小;当偏压显著增大时,隧穿电导和TMR随势垒层厚度振荡的振幅和频率均随之减小。

Based on the Bethe theory and the two-beam approximation,a theoretical model was developed for the magnetic tunnel junctions with single crystal 2D-material barrier.In the model,the single crystal barrier was treated as a diffraction grating.As a result,the coherence of tunneling electrons can be well considered.Furthermore,the theory was used to calculate the effect of bias voltage on the magnetic tunnel junctions with the single crystal 2D-material barrier.The numerical simulation reveals how the ferromagnetic electrodes affect the effect of bias voltage and how bias voltage affect the effect of thickness.The results show that,owing to the coherence caused by the scattering of periodic barrier on the transmitted electron wave,the tunneling conductance and TMR will oscillate with the bias voltage.And the period of the oscillation increases with half of the exchange splitting of the ferromagnetic electrodes.In addition,when the bias voltage is lower than 100 mV,it has slight effect on the tunneling magnetoresistance.When the bias voltage increases significantly,the amplitude and frequency of the TMR oscillations will both decrease.