By the rate equation method in sequential and cotunneling regimes, we study the transport current and tunnel magnetoresistance through a single molecule magnet asymmetrically coupled to two collinear ferromagnetic electrodes. It is observed that the direction of spin-polarization current can be inversed by spin bias voltage and the adjacent magnetic field changed with left lead’s polarization. As a consequence, the tunnel magnetoresistance can reach exceptional values beyond the usual restriction of −1 to +1. Moreover, since charge current can be zero in parallel configuration and spin current stays positive, the pure spin current appears. Thus, the system may act as a spin-valve device.

中文翻译：

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自旋极化电流的方向反转和异常的隧道磁阻

通过速率方程法在顺序和共隧道方法中，我们研究了通过不对称耦合到两个共线铁磁电极的单分子磁体的传输电流和隧道磁阻。可以看出，自旋偏置电压可以使自旋极化电流的方向反转，并且相邻磁场随左引线的极化而改变。结果，隧道磁阻可以达到超出通常限制-1至+1的异常值。此外，由于在并联配置中充电电流可以为零，并且自旋电流保持为正，因此会出现纯自旋电流。因此，该系统可以充当旋转阀装置。