Search for the mechanism of the spin Hall effect

我们研究了铜基合金中的非本征自旋霍尔效应。铜具有非常弱的自旋-轨道(SO)相互作用，而且铜本身的SHE可以忽略不计。然而，通过加入具有较强SO相互作用的杂质，如Ir和Bi，可以产生非本征SHE。与纯Se材料如铂和Pd不同，外源Se材料的一大优点是它允许通过改变基质和杂质金属的组合以及调节杂质浓度来控制SH角，这是电荷和自旋之间的转化率的特征。通过掺入Ir杂质，我们观察到了清晰的Se信号。根据SH电阻率随掺杂浓度变化的斜率，我们估计SH角为2%。用铋取代Ir杂质后，得到的SH角比CuIr合金大一个数量级以上。

We have studied extrinsic spin Hall effect(SHE) in Cu-based alloys. Copper has a very weak spin-orbit(SO) interaction and the SHE of Cu itself is negligibly small. However, by adding impurities with strong SO interactions such as Ir and Bi, the extrinsic SHEs can be generated. Unlike pure SHE materials such as Pt and Pd, one of the big advantages for the extrinsic SHE is that it allows controlling the SH angle, characteristic of the conversion yield between charge and spin, by changing the combination of host and impurity metals as well as by tuning the impurity concentration. By doping with Ir impurities, we observe a clear SHE signal. From the slope of the SH resistivity as a function of doping concentration, we estimate the SH angle to be 2%. When Ir impurities are replaced by Bi ones, the obtained SH angle is more than one order larger than that of CuIr alloys.