Department of Physics, The Ohio State University , Columbus, Ohio 43210, United States.
Department of Chemical Engineering and Materials Science, University of Minnesota , Minneapolis, Minnesota 55455, United States.
Nano Lett. 2017 Dec 13;17(12):7578-7585. doi: 10.1021/acs.nanolett.7b03543. Epub 2017 Nov 16.
The quality of the tunnel barrier at the ferromagnet/graphene interface plays a pivotal role in graphene spin valves by circumventing the impedance mismatch problem, decreasing interfacial spin dephasing mechanisms and decreasing spin absorption back into the ferromagnet. It is thus crucial to integrate superior tunnel barriers to enhance spin transport and spin accumulation in graphene. Here, we employ a novel tunnel barrier, strontium oxide (SrO), onto graphene to realize high quality spin transport as evidenced by room-temperature spin relaxation times exceeding a nanosecond in graphene on silicon dioxide substrates. Furthermore, the smooth and pinhole-free SrO tunnel barrier grown by molecular beam epitaxy (MBE), which can withstand large charge injection current densities, allows us to experimentally realize large spin accumulation in graphene at room temperature. This work puts graphene on the path to achieve efficient manipulation of nanomagnet magnetization using spin currents in graphene for logic and memory applications.
铁磁体/石墨烯界面的隧道势垒质量对于石墨烯自旋阀至关重要，它可以避免阻抗不匹配问题、减少界面自旋退相干机制并减少自旋重新进入铁磁体的吸收。因此，集成优异的隧道势垒对于增强石墨烯中的自旋输运和自旋积累至关重要。在这里，我们在石墨烯上采用了一种新型的隧道势垒——氧化锶 (SrO)，从而实现了高质量的自旋输运，在二氧化硅衬底上的石墨烯中室温自旋弛豫时间超过了纳秒。此外，通过分子束外延 (MBE) 生长的光滑无针孔 SrO 隧道势垒可以承受大的电荷注入电流密度，使我们能够在室温下实验上实现石墨烯中的大自旋积累。这项工作使石墨烯能够通过在石墨烯中利用自旋流来有效地控制纳米磁体的磁化，从而实现逻辑和存储应用。
