Khalil Lama, Pierucci Debora, Velez-Fort Emilio, Avila José, Vergnaud Céline, Dudin Pavel, Oehler Fabrice, Chaste Julien, Jamet Matthieu, Lhuillier Emmanuel, Pala Marco, Ouerghi Abdelkarim
Université Paris-Saclay, CNRS, Centre de Nanosciences et de Nanotechnologies, F-91120, Palaiseau, France.
Université Grenoble Alpes, CEA, CNRS, Grenoble INP, IRIG-Spintec, F-38054, Grenoble, France.
Nanotechnology. 2022 Nov 7;34(4). doi: 10.1088/1361-6528/ac9abe.
Nearly localized moiré flat bands in momentum space, arising at particular twist angles, are the key to achieve correlated effects in transition-metal dichalcogenides. Here, we use angle-resolved photoemission spectroscopy (ARPES) to visualize the presence of a flat band near the Fermi level of van der Waals WSe/MoSeheterobilayer grown by molecular beam epitaxy. This flat band is localized near the Fermi level and has a width of several hundred meVs. By combining ARPES measurements with density functional theory calculations, we confirm the coexistence of different domains, namely the reference 2H stacking without layer misorientation and regions with arbitrary twist angles. For the 2H-stacked heterobilayer, our ARPES results show strong interlayer hybridization effects, further confirmed by complementary micro- Raman spectroscopy measurements. The spin-splitting of the valence band atis determined to be 470 meV. The valence band maximum (VBM) position of the heterobilayer is located at the Γ point. The energy difference between the VBM at Γ and thepoint is of -60 meV, which is a stark difference compared to individual single monolayer WSeand monolayer WSe, showing both a VBM at.
在动量空间中，近局域化的莫尔平带出现在特定的扭转角处，是在过渡金属二硫属化物中实现关联效应的关键。在这里，我们使用角分辨光电子能谱（ARPES）来观察通过分子束外延生长的范德华WSe/MoSe异质双层费米能级附近平带的存在。这个平带局域在费米能级附近，宽度为几百毫电子伏特。通过将ARPES测量与密度泛函理论计算相结合，我们证实了不同畴的共存，即没有层错取向的参考2H堆叠以及具有任意扭转角的区域。对于2H堆叠的异质双层，我们的ARPES结果显示出强烈的层间杂化效应，互补的显微拉曼光谱测量进一步证实了这一点。价带在处的自旋分裂确定为470毫电子伏特。异质双层的价带最大值（VBM）位置位于Γ点。Γ点处的VBM与点之间的能量差为-60毫电子伏特，与单个单层WSe和单层WSe相比有明显差异，两者在处均显示出VBM。
