扭曲二硫化钼双层中层间耦合的演变。
Evolution of interlayer coupling in twisted molybdenum disulfide bilayers.
机构信息
1] Department of Physics, University of California at Berkeley, Berkeley, California 94720, USA [2] State Key Laboratory for Mesoscopic Physics, School of Physics and Collaborative Innovation Center of Quantum Matter, Peking University, Beijing 100871, China.
Department of Chemistry, University of California at Berkeley, Berkeley, California 94720, USA.
出版信息
Nat Commun. 2014 Sep 18;5:4966. doi: 10.1038/ncomms5966.
Van der Waals coupling is emerging as a powerful method to engineer physical properties of atomically thin two-dimensional materials. In coupled graphene-graphene and graphene-boron nitride layers, interesting physical phenomena ranging from Fermi velocity renormalization to Hofstadter's butterfly pattern have been demonstrated. Atomically thin transition metal dichalcogenides, another family of two-dimensional-layered semiconductors, can show distinct coupling phenomena. Here we demonstrate the evolution of interlayer coupling with twist angles in as-grown molybdenum disulfide bilayers. We find that the indirect bandgap size varies appreciably with the stacking configuration: it shows the largest redshift for AA- and AB-stacked bilayers, and a significantly smaller but constant redshift for all other twist angles. Our observations, together with ab initio calculations, reveal that this evolution of interlayer coupling originates from the repulsive steric effects that leads to different interlayer separations between the two molybdenum disulfide layers in different stacking configurations.
范德华耦合正成为一种强大的方法，用于设计原子薄二维材料的物理性质。在耦合的石墨烯-石墨烯和石墨烯-氮化硼层中，已经证明了从费米速度重整化到霍夫斯塔特蝴蝶图案等有趣的物理现象。原子薄的过渡金属二卤化物，另一种二维层状半导体家族，也可以表现出明显的耦合现象。在这里，我们展示了在生长的二硫化钼双层中随扭转角的层间耦合演变。我们发现，间接带隙大小随堆叠结构明显变化：AA 和 AB 堆叠双层的红移最大，而所有其他扭转角的红移则显著较小但恒定。我们的观察结果与从头算计算一起表明，这种层间耦合的演变源自排斥的空间效应，这导致了不同堆叠结构中两层二硫化钼之间不同的层间分离。
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