将不同的二维材料进行堆叠形成异质结形式，可以综合不同组分的新奇物理特性，同时还能弥补各自的缺点，为二维材料的应用打开了新方向。将过渡金属硫化物（TMDs）与本征磁性二维材料结合成异质结，利用界面间产生的磁近邻效应，可以破坏TMDs中相邻能谷的能级简并。在二维范德瓦尔斯异质结中，可以通过调控上下两层材料相互扭转，从而对其电子、磁性质进行精准调控，是异质结性能调控的新变量。该研究通过对不同扭转角度的WSe2和CrI3进行堆叠，发现扭转可以加强上下两原子层间耦合。来自山西师范大学的张均锋教授团队与美国伦斯勒理工学院的张绳百教授及其合作者们，利用第一性原理考察了不同扭转角下，二维范德瓦尔斯WSe2/CrI3异质结的结构稳定性、电子和磁性质。发现随着扭转角度的变大，异质结变得越来越稳定。更为重要的是，发现WSe2中的能谷劈裂，与非扭转的堆叠方式相比，有十几倍的显著增强。这揭示了扭转的范德瓦尔斯异质结中能谷劈裂增强与上下两层原子之间的耦合强度有着很大的关系。量子力学模型分析等效磁场发现，扭转角为23.4o的异质结中产生的能谷劈裂值，相当于将WSe2放置于20.9T的超高强度磁场中产生的劈裂值大小。这一工作，为TMDs中能谷劈裂调控提供了新的方向。

Editorial Summary

Two-dimensional van der Waals heterostructures: twist makes miracles！ 

Van der Waals (vdW) heterostructures composed of different two-dimensional (2D) materials offer an easily accessible way to combine properties of individual materials for applications. The magnetic proximity effect at interfaces of 2D vdW heterostructures formed by transition metal dichalcogenides (TMDs) and intrinsic magnetic materials, can break the time-reversal symmetry and degenerate energy valleys in momentum space. Further on, 2D vdW twisted heterostructures, in which one layer is rotated with respect to the other by an angle, are also interesting. Twist may be new variable to tune the properties of electronic and magnetic. The enhanced coupling of atoms between the upper and lower layers of the twisted vdW WSe2/CrI3 heterostructures is reported in this work. A team led by Prof. Junfeng Zhang from Shanxi Normal University, Prof. Shengbai Zhang from Rensselaer Polytechnic Institute, USA, and their coworkers, investigated a set of 2D vdW WSe2/CrI3 heterostructures with different twist angle with an emphasis on the magnetic properties, using first-principles calculation. The results of the formation energy indicate that the twisted heterostructures are more stable than non-twisted ones. More importantly, in twisted heterostructures, there is an order of magnitude enhancement of valley splitting. The analysis of the partial charge density suggests that the coupling of Cr atoms and W atoms is responsible for the enhanced valley splitting. With the help of a k？p model, the equivalent magnetic field is deduced (for the 23.4 twist angle, the equivalent magnetic field CrI3 generated is about 20.9T, corresponding to 5.18meV valley splitting in WSe2). It shows that not only the magnetic field strength is sufficiently strong but also twisting can be an effective way to amplify the magnetic proximity effect at interfaces.