Search for the mechanism of the spin Hall effect

研究了铜基合金中的自旋霍尔效应（SHE）。铜具有非常弱的自旋轨道相互作用，铜本身的SHE小得可以忽略不计。然而，通过添加具有强SO相互作用的杂质，如Ir和Bi，可以产生外源性she。与纯SHE材料（如Pt和Pd）不同，外源SHE的一大优点是，它可以通过改变宿主金属和杂质金属的组合以及调整杂质浓度来控制SH角，这是电荷和自旋之间转换产率的特征。通过掺杂Ir杂质，我们观察到一个清晰的SHE信号。根据SH电阻率随掺杂浓度的斜率，我们估计SH角为2%。当用Bi杂质代替Ir杂质时，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.