The low-energy band structure of few-layer ${\mathrm{MoS}}_2$ is relevant for a large variety of experiments ranging from optics to electronic transport. Its characterization remains challenging due to complex multiband behavior. We investigate the conduction band of dual-gated three-layer ${\mathrm{MoS}}_2$ by means of magnetotransport experiments. The total carrier density is tuned by voltages applied between ${\mathrm{MoS}}_2$ and both top and bottom gate electrodes. For asymmetrically biased top and bottom gates, electrons accumulate in the layer closest to the positively biased electrode. In this way, the three-layer ${\mathrm{MoS}}_2$ can be tuned to behave electronically like a monolayer. In contrast, applying a positive voltage on both gates leads to the occupation of all three layers. Our analysis of the Shubnikov–de Haas oscillations originating from different bands lets us attribute the corresponding carrier densities in the top and bottom layers. We find a twofold Landau level degeneracy for each band, suggesting that the minima of the conduction band lie at the $\pm K$ points of the first Brillouin zone. This is in contrast to band structure calculations for zero layer asymmetry, which report minima at the $Q$ points. Even though the interlayer tunnel coupling seems to leave the low-energy conduction band unaffected, we observe scattering of electrons between the outermost layers for zero layer asymmetry. The middle layer remains decoupled due to the spin-valley symmetry, which is inverted for neighboring layers. When the bands of the outermost layers are energetically in resonance, interlayer scattering takes place, leading to an enhanced resistance and to magneto-interband oscillations.

中文翻译：

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双门三层MoS2中的电子传输

几层的低能带结构 ${\mathrm{硫化钼}}_{\mathrm{2个}}$与从光学到电子传输的各种各样的实验有关。由于复杂的多频带行为，其表征仍然具有挑战性。我们研究双门三层的导带${\mathrm{硫化钼}}_{\mathrm{2个}}$通过磁运输实验。总载流子密度可通过施加在两个载流子之间的电压来调节${\mathrm{硫化钼}}_{\mathrm{2个}}$以及顶部和底部栅电极。对于不对称偏置的顶部和底部栅极，电子在最靠近正偏置电极的层中积累。这样，三层${\mathrm{硫化钼}}_{\mathrm{2个}}$可以调整为像单层电子行为。相反，在两个栅极上都施加正电压会导致全部三个层被占用。我们对源自不同频带的Shubnikov-de Haas振荡的分析使我们可以将顶层和底层的相应载流子密度归因于。我们发现每个带都有两倍的Landau能级简并性，这表明传导带的最小值位于$\pm ķ$第一个布里渊区的位置。这与零层不对称性的能带结构计算相反，后者在零层不对称处报告极小值。$问$点。即使层间隧道耦合似乎使低能导带不受影响，对于零层不对称性，我们也观察到了最外层之间的电子散射。由于自旋谷对称性，中间层保持解耦，自旋谷对称性对于相邻层是相反的。当最外层的带在能量上共振时，发生层间散射，导致增强的电阻并引起磁间带振动。