有机自旋阀的磁电阻性质研究

Magnetoresistance effect in an organic spin valve

考虑到有机半导体中极化子和双极化子特殊的电荷-自旋关系,从自旋扩散方程和欧姆定律出发,理论研究了"铁磁/有机半导体/铁磁"有机自旋阀结构中的磁电阻性质.计算发现,磁电阻在数值上随有机半导体层中极化子比率的增加而增大,随有机半导体层厚度的增加而迅速减小.同时发现自旋相关界面电阻能在很大程度上提高系统的磁电阻.讨论了铁磁层和有机半导体电导率比率、铁磁层极化率等对系统磁电阻性质的影响.

Based on the spin diffusion theory and the Ohm’s law,we theoretically studied the magnetoresistance （MR） effect in an organic spin valve with structure of ferromagnetic /organic semiconductor /ferromagnetic system,which takes into account the special characteristics of organic semiconductors. Self-trapped states,such as spin polarons as well as spinless bipolarons are assumed to be the main carriers in organic semiconductors. From the calculation,it is found that MR ratio increases with the increasing of the polaron proportion and rapidly decreases with the increasing of the organic layer thickness. MR ratio can be enhanced remarkably when the interfacial resistances are spin related. Effects of the conductivity match and the spin polarization of the ferromagnetic layer on the MR are also discussed.