Ulstrup Søren, Koch Roland J, Singh Simranjeet, McCreary Kathleen M, Jonker Berend T, Robinson Jeremy T, Jozwiak Chris, Rotenberg Eli, Bostwick Aaron, Katoch Jyoti, Miwa Jill A
Department of Physics and Astronomy, Aarhus University, 8000 Aarhus C, Denmark.
Advanced Light Source, E. O. Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
Sci Adv. 2020 Apr 3;6(14):eaay6104. doi: 10.1126/sciadv.aay6104. eCollection 2020 Apr.
Stacking two-dimensional (2D) van der Waals materials with different interlayer atomic registry in a heterobilayer causes the formation of a long-range periodic superlattice that may bestow the heterostructure with properties such as new quantum fractal states or superconductivity. Recent optical measurements of transition metal dichalcogenide (TMD) heterobilayers have revealed the presence of hybridized interlayer electron-hole pair excitations at energies defined by the superlattice potential. The corresponding quasiparticle band structures, so-called minibands, have remained elusive, and no such features have been reported for heterobilayers composed of a TMD and another type of 2D material. We introduce a new x-ray capillary technology for performing microfocused angle-resolved photoemission spectroscopy with a spatial resolution of ~1 μm, and directly observe minibands at certain twist angles in mini Brillouin zones (mBZs). We discuss their origin in terms of initial and final state effects by analyzing their dispersion in distinct mBZs.
在异质双层中堆叠具有不同层间原子排列的二维（2D）范德华材料会导致形成长程周期性超晶格，这可能赋予异质结构诸如新的量子分形态或超导性等特性。最近对过渡金属二卤化物（TMD）异质双层的光学测量揭示了在由超晶格势定义的能量处存在杂化的层间电子-空穴对激发。相应的准粒子能带结构，即所谓的微带，仍然难以捉摸，并且对于由TMD和另一种类型的二维材料组成的异质双层，尚未有此类特征的报道。我们引入了一种新的X射线毛细管技术，用于执行空间分辨率约为1μm的微聚焦角分辨光电子能谱，并直接在微型布里渊区（mBZ）的特定扭转角处观察到微带。我们通过分析它们在不同mBZ中的色散，从初态和终态效应的角度讨论了它们的起源。
