Controlling the interlayer twist angle offers a powerful means for tuning the electronic properties of two-dimensional (2D) van der Waals materials. Typically, the electrical conductivity would increase monotonically with decreasing twist angle owing to the enhanced coupling between adjacent layers. Here, we report a nonmonotonic angle-dependent vertical conductivity across the interface of bilayer graphene with low twist angles. More specifically, the vertical conductivity enhances gradually with decreasing twist angle up to a crossover angle at θ_c ≈ 5°, and then it drops notably upon further decrease in the twist angle. Revealed by density functional theory calculations and scanning tunneling microscopy, the abnormal behavior is attributed to the unusual reduction in average carrier density originating from local atomic reconstruction. The impact of atomic reconstruction on vertical conductivity is unique for low-angle twisted 2D van der Waals materials and provides a strategy for designing and optimizing their electronic performance.

控制层间扭曲角为调整二维（2D）范德华材料的电子性能提供了强大的手段。典型地，由于相邻层之间的增强的耦合，电导率将随着扭转角的减小而单调增加。在这里，我们报告了低扭曲角的双层石墨烯界面上非单调角度相关的垂直电导率。更具体地，垂直导电率逐渐增强与在θ减小扭转角高达交叉角度_Ç≈5°，然后随着扭转角的进一步减小而明显下降。通过密度泛函理论计算和扫描隧道显微镜显示，异常行为归因于源自局部原子重建的平均载流子密度的异常降低。原子重构对垂直电导率的影响对于低角度扭曲2D范德华材料来说是独特的，并提供了设计和优化其电子性能的策略。