磁电势垒结构中光场辅助电子自旋输运特性

Light-field assisted spin-polarized transport properties in magnetic-electric barrier structures

基于Floquet理论和传输矩阵方法,理论研究了光场对电子隧穿两类磁电垒结构的自旋极化输运特性的影响,计算结果表明光场对两类磁电垒结构中电子的输运有显著影响:首先,原来不存在自旋过滤特性的结构应用光场后会产生低能区域明显的自旋过滤效应;其次,原来存在自旋过滤特性的结构应用光场后自旋过滤明显增强,增幅超过一个数量级.这些为新的自旋极化源的产生和自旋过滤现象的深入研究有一定的指导性意义.

Based on the Floquet theory and transfer-matrix method,We investigated the influence of light-field on the spin-polarized transport properties for electrons tunneling through two kinds of magnetic-electric barrier structures(the δ-doped magnetic-barrier can be realized in experiments by depositing two ferromagnetic stripes on top and bottom of a semiconductor heterostructure and the light-field can be realized by placing a hemispherical silicon lens on the back surface of the semiconductor substrate).Transport properties result from the interaction of electrons with the light-field by means of photon absorption and emission.It is found that the light-field can greatly affect the transmission probabilities as well as the corresponding polarizations.The distance between the adjacent peaks and the number of the transport peaks can be controlled by adjusting the frequency and the amplitude of the light-field,respectively.It is shown that a significant spin-polarization effect can be induced by such light-field in the kind of antisymmetric magnetic barrier structure(B1=-B2) and the light-field can greatly change the spin-polarization effect in the kind of symmetric magnetic barrier structure(B1=B2).When the frequency of the light-field increases,the spin-polarization shifts toward the low-energy end and gradually increases.These remarkable properties of spin polarization may be beneficial for the devising tunable spin filtering devices.