Spin Lifetimes Exceeding 12 ns in Graphene Nonlocal Spin Valve Devices
Spin Lifetimes Exceeding 12 ns in Graphene Nonlocal Spin Valve Devices
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DOI：
10.1021/acs.nanolett.6b00497
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发表时间：
2016-06-01
期刊：
影响因子：
10.8
通讯作者：
Beschoten, Bernd
中科院分区：
文献类型：
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作者：
Droegeler, Marc;Franzen, Christopher;Beschoten, Bernd
我们显示自旋寿命为12.6纳秒和自旋扩散长度长达30.5 μ m的单层石墨烯非局域自旋输运器件在室温下。这是通过在Si/SiO2基底上制造Co/MgO电极和随后在该电极结构的顶部上干法转移石墨烯-hBN叠层来实现的，其中需要大的hBN薄片以减少溶剂沿着hBN-基底界面的进入。有趣的是，尽管导电扫描力显微镜和接触电阻测量揭示了整个MgO自旋注入/检测势垒的导电针孔的存在，观察到长的自旋寿命。与以前的设备相比，我们观察到单层石墨烯的自旋寿命提高了6倍。我们表明，自旋寿命不依赖于接触电阻面积的产品时，比较所有自下而上的设备，表明自旋吸收在接触的自旋退相的主要来源。
We show spin lifetimes of 12.6 ns and spin diffusion lengths as long as 30.5 mu m in single layer graphene nonlocal spin transport devices at room temperature. This is accomplished by the fabrication of Co/MgO-electrodes on a Si/SiO2 substrate and the subsequent dry transfer of a graphene-hBN-stack on top of this electrode structure where a large hBN flake is needed in order to diminish the ingress of solvents along the hBN-to-substrate interface. Interestingly, long spin lifetimes are observed despite the fact that both conductive scanning force microscopy and contact resistance measurements reveal the existence of conducting pinholes throughout the MgO spin injection/detection barriers. Compared to previous devices, we observe an enhancement of the spin lifetime in single layer graphene by a factor of 6. We demonstrate that the spin lifetime does not depend on the contact resistance area products when comparing all bottom-up devices indicating that spin absorption at the contacts is not the predominant source for spin dephasing.