Spin polarized coulomb blockade in metallic magnetic single electron transistors

磁电子学在当今和未来的信息技术中扮演着重要的角色。随着未来磁电子器件尺寸的稳步减小，充电能量增加，库仑阻塞效应可能最终主导自旋相关的输运。虽然关于自旋极化库仑阻塞的各种理论预测都是可用的，但实验研究很少，而且缺乏完整的图景。在这里，我们建议研究金属磁单电子晶体管(MagSET)岛与自旋极化良好的铁磁引线耦合的模型系统中的自旋极化库仑阻塞。利用磁性双势垒隧道结(DBTJ)制作了亚微米级的磁集电极。在这些器件中，引线的矫顽场和初始自旋取向由其生长参数和与反铁磁层的耦合控制。所提出的磁集电极允许使用倾斜磁场精确地控制两个引线的相对自旋极化。自旋相关的单电子输运以倾斜磁场中MK温度下的低温磁输运为特征。此外，还从理论上分析了器件的自旋相关输运行为及其可能的机制，并与实验观测结果进行了比较。该项目将首次实现对磁性金属单电子晶体管中与自旋相关的单电子隧穿的完整理解。

Magneto electronics plays a major role in todays and future information technology. With steadily decreasing dimensions of future magneto electronics devices the charging energy increases and coulomb blockade effects may eventually dominate spin dependent transport. While various theoretical predictions on spin polarized coulomb blockade are available only very few experimental studies exist and a complete picture is lacking. Here we propose to study spin polarized coulomb blockade in the model system of a metallic magnetic single electron transistor (magSET) island coupled to ferromagnetic leads of well controlled spin polarization. The sub micron magSETs are fabricated from magnetic double barrier tunnelling junctions (DBTJ). In these devices the coercive field and the initial spin orientation of the leads is controlled by its growth parameters and coupling to antiferromagnetic layers. The proposed magSETs allow a precise control of the relative spin polarization of the two leads using a tilted magnetic field. The spin dependent single electron transport is characterized by low temperature magneto transport at mK temperatures in tilted magnetic fields. Additionally the spin dependent transport behaviour of the devices and the underlying mechanisms is analyzed theoretically and compared to the experimental observations. This project will for the first time allow a complete understanding of spin dependent single electron tunnelling in magnetic metallic single electron transistors.