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中国物理学会期刊

石墨烯中选择性增强Kane-Mele型自旋-轨道相互作用

CSTR: 32037.14.aps.71.20211815

Selective enhancement of Kane Mele-type spin-orbit interaction in graphene

CSTR: 32037.14.aps.71.20211815
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  • 增强石墨烯中的自旋-轨道相互作用可能实现无耗散的量子自旋霍尔器件, 这需要在石墨烯样品中引入独特的Kane-Mele型自旋-轨道相互作用, 并保持较高的迁移率. 然而, 对石墨烯的外在修饰往往会引入“外禀型”Rashba自旋-轨道相互作用, 会破坏可能存在的拓扑态, 并带来一定程度的杂质散射, 降低样品迁移率. 在石墨烯表面修饰EDTA-Dy分子后, 载流子迁移率得到了提高, 并且可以看到显著的量子霍尔电导平台. 其弱局域化效应相比被修饰之前得到了抑制, 这意味石墨烯中可能引入了内禀的Kane-Mele型自旋-轨道相互作用, 增强了Elliot-Yafet型电子自旋弛豫机制. 进一步通过矢量磁体磁阻测量, 发现该分子覆盖在石墨烯上后造成了石墨烯微弱的涟漪, 这种涟漪引起的弯曲声子效应模拟了Kane-Mele型自旋-轨道相互作用.

     

    In order to enhance the spin orbit interaction (SOI) in graphene for seeking the dissipationless quantum spin Hall devices, unique Kane-Mele-type SOI and high mobility samples are desired. However, the common external modification of graphene often introduces “extrinsic” Rashba-type SOI, which will destroy the possible topological state, bring a certain degree of impurity scattering and reduce the sample mobility. Here we show that by the EDTA-Dy molecule dressing, the carrier mobility is even improved, and the quantum Hall plateaus are observed more clearly. The Kane-Mele type SOI is mimicked after dressing, which is evidenced by the suppressed weak localization at equal carrier densities and simultaneous Elliot-Yafet spin relaxation. This is attributed to the spin-flexural phonon coupling induced by the enhanced graphene ripples, as revealed by the in-plane magnetotransport measurement.

     

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