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arXiv 1305.2602cond-mat.mtrl-scicond-mat.mes-hall
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锗的自旋抽运和反自旋霍尔效应

Spin Pumping and Inverse Spin Hall Effect in Germanium

J. -C. Rojas-Sánchez, M. Cubukcu, A. Jain, C. Vergnaud, C. Portemont, C. Ducruet, A. Barski, A. Marty, L. Vila, J. -P. Attané, E. Augendre, G. Desfonds, S. Gamb… 展开作者

J. -C. Rojas-Sánchez, M. Cubukcu, A. Jain, C. Vergnaud, C. Portemont, C. Ducruet, A. Barski, A. Marty, L. Vila, J. -P. Attané, E. Augendre, G. Desfonds, S. Gambarelli, H. Jaffrès, J. -M. George, M. Jamet

摘要:

我们在室温下测量了\textit{n} -Ge的逆自旋霍尔效应(ISHE)。锗中的自旋电流是通过自旋泵从CoFeB/MgO磁性隧道结产生的,以防止阻抗失配问题。在CoFeB的铁磁共振下,在Ge中测量到明显的电动势。同样的研究,然后进行了几个测试样品,特别是我们已经调查了MgO隧道势垒和样品退火对ISHE信号的影响。首先,生长在$_{2}$上的参考CoFeB/MgO双层膜由于各向异性磁阻和异常霍尔效应而表现出明显的电动势,所述异常霍尔效应由相对于谐振场的不对称贡献主导。我们还发现,MgO隧道势垒是必不可少的观察ISHE在Ge和样品退火系统导致信号的增加。我们提出了一个理论模型的基础上存在的本地化状态之间的界面上的MgO隧道势垒和锗占这些意见。最后,我们的所有结果与重掺杂$n$ -Ge中ISHE的观察完全一致,并且我们可以估计室温下的自旋霍尔角为$\approx$ 0.001。

英文摘要:

We have measured the inverse spin Hall effect (ISHE) in \textit{n}-Ge at room temperature. The spin current in germanium was generated by spin pumping from a CoFeB/MgO magnetic tunnel junction in order to prevent the impedance mismatch issue. A clear electromotive force was measured in Ge at the ferromagnetic resonance of CoFeB. The same study was then carried out on several test samples, in particular we have investigated the influence of the MgO tunnel barrier and sample annealing on the ISHE signal. First, the reference CoFeB/MgO bilayer grown on SiO$_{2}$ exhibits a clear electromotive force due to anisotropic magnetoresistance and anomalous Hall effect which is dominated by an asymmetric contribution with respect to the resonance field. We also found that the MgO tunnel barrier is essential to observe ISHE in Ge and that sample annealing systematically lead to an increase of the signal. We propose a theoretical model based on the presence of localized states at the interface between the MgO tunnel barrier and Ge to account for these observations. Finally, all of our results are fully consistent with the observation of ISHE in heavily doped $n$-Ge and we could estimate the spin Hall angle at room temperature to be $\approx$0.001.

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