Solid State Physics Laboratory, ETH Zürich, 8093 Zürich, Switzerland.
National Institute for Material Science, 1-1 Namiki, Tsukuba 305-0044, Japan.
Phys Rev Lett. 2019 Sep 13;123(11):117702. doi: 10.1103/PhysRevLett.123.117702.
In Bernal stacked bilayer graphene interlayer coupling significantly affects the electronic band structure compared to monolayer graphene. Here we present magnetotransport experiments on high-quality n-doped bilayer MoS_{2}. By measuring the evolution of the Landau levels as a function of electron density and applied magnetic field we are able to investigate the occupation of conduction band states, the interlayer coupling in pristine bilayer MoS_{2}, and how these effects are governed by electron-electron interactions. We find that the two layers of the bilayer MoS_{2} behave as two independent electronic systems where a twofold Landau level's degeneracy is observed for each MoS_{2} layer. At the onset of the population of the bottom MoS_{2} layer we observe a large negative compressibility caused by the exchange interaction. These observations, enabled by the high electronic quality of our samples, demonstrate weak interlayer tunnel coupling but strong interlayer electrostatic coupling in pristine bilayer MoS_{2}. The conclusions from the experiments may be relevant also to other transition metal dichalcogenide materials.
在伯纳尔堆叠双层石墨烯中，与单层石墨烯相比，层间耦合会显著影响电子能带结构。在这里，我们展示了对高质量 n 型掺杂双层 MoS_{2} 的输运实验。通过测量作为电子密度和外加磁场函数的朗道能级的演化，我们能够研究导带态的占据情况、原始双层 MoS_{2} 的层间耦合，以及这些效应如何受到电子-电子相互作用的控制。我们发现，双层 MoS_{2} 的两层表现为两个独立的电子系统，其中每个 MoS_{2}层的朗道能级简并度为两倍。在底部 MoS_{2}层的占据开始时，我们观察到由于交换相互作用引起的大的负压缩性。这些观察结果，得益于我们样品的高电子质量，表明原始双层 MoS_{2} 中的层间隧道耦合较弱，但层间静电耦合较强。实验得出的结论可能也与其他过渡金属二卤化物材料有关。
