Joseph Henry Laboratory, Department of Physics, Princeton University, Princeton, New Jersey 08544, USA.
Center for Condensed Matter Sciences, National Taiwan University, Taipei 10617, Taiwan.
Nat Commun. 2014 Aug 22;5:4673. doi: 10.1038/ncomms5673.
Transition metal dichalcogenides [corrected] have attracted much attention recently due to their potential applications in spintronics and photonics because of the indirect to direct band gap transition and the emergence of the spin-valley coupling phenomenon upon moving from the bulk to monolayer limit. Here, we report high-resolution angle-resolved photoemission spectroscopy on MoSe2 single crystals and monolayer films of MoS2 grown on highly ordered pyrolytic graphite substrate. Our experimental results resolve the Fermi surface trigonal warping of bulk MoSe2, and provide evidence for the critically important spin-orbit split valence bands of monolayer MoS2. Moreover, we systematically image the formation of quantum well states on the surfaces of these materials, and present a theoretical model to account for these experimental observations. Our findings provide important insights into future applications of transition metal dichalcogenides in nanoelectronics, spintronics and photonics devices as they critically depend on the spin-orbit physics of these materials.
过渡金属二卤族化合物[已更正]由于其在自旋电子学和光子学中的潜在应用而受到了广泛关注，因为在从体相到单层极限的转变过程中会发生间接到直接带隙跃迁，并且出现了自旋-谷耦合现象。在这里，我们报告了在高度有序的热解石墨衬底上生长的 MoSe2 单晶和 MoS2 单层薄膜的高分辨率角分辨光发射谱。我们的实验结果解决了体相 MoSe2 的费米表面三角扭曲问题，并为单层 MoS2 至关重要的自旋轨道分裂价带提供了证据。此外，我们系统地描绘了这些材料表面上量子阱态的形成，并提出了一个理论模型来解释这些实验观察结果。我们的发现为过渡金属二卤族化合物在纳米电子学、自旋电子学和光子学器件中的未来应用提供了重要的见解，因为它们严重依赖于这些材料的自旋轨道物理。
