Tunnel spin polarization of Fe/MgO/Si contacts reaching 90% with increasing MgO thickness
Tunnel spin polarization of Fe/MgO/Si contacts reaching 90% with increasing MgO thickness
复制标题
隧道%20自旋%20极化%20of%20Fe/MgO/Si%20接触%20到达%2090%%20with%20增加%20MgO%20厚度
DOI：
10.1103/physrevb.99.224427
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发表时间：
2019
影响因子：
3.7
通讯作者：
R. Jansen
中科院分区：
文献类型：
--
作者：
A. Spiesser;H. Saito;S. Yuasa;R. Jansen
利用非局域自旋输运器件，测定了Si上Fe/MgO隧道接触的隧道自旋极化（TSP）随MgO厚度的变化. TSP，提取的非本地自旋阀和汉勒信号的幅度，MgO厚度的增加，并示出在低温下达到约90%的值。这样一个近乎完美的自旋极化的隧道电流表明，由于相干隧穿发生在Si上的Fe/MgO隧道接触，尽管显着的晶格失配基于自旋过滤。对于MgO厚度低于1 nm，TSP出乎意料地快速下降（至低于25%的值），这归因于薄MgO层的较低结晶质量。事实上，数据表明，Si上的前0.7 nm的MgO对自旋过滤的贡献非常小。
Using nonlocal spin-transport devices, the tunnel spin polarization (TSP) of Fe/MgO tunnel contacts on Si is determined as a function of the thickness of the MgO. The TSP, extracted from the magnitude of the nonlocal spin-valve and Hanle signals, increases with MgO thickness and is shown to reach values of around 90% at low temperatures. Such a near-perfect spin polarization of the tunnel current indicates that symmetry-based spin filtering due to coherent tunneling occurs in Fe/MgO tunnel contacts on Si, despite the significant lattice mismatch. For MgO thicknesses below 1 nm, the TSP drops unexpectedly rapidly (to values below 25%), which is attributed to the lower crystalline quality of thin MgO layers. In fact, the data suggest that the first 0.7 nm of MgO on the Si contributes very little to the spin filtering.