Understanding the interfacial properties between an atomic layer and its substrate is of key interest at both the fundamental and technological levels. From Fermi level pinning to strain engineering and superlubricity, the interaction between a single atomic layer and its substrate governs electronic, mechanical and chemical properties. Here, we measure the hardly accessible interfacial transverse shear modulus of an atomic layer on a substrate. By performing measurements on bulk graphite, and on epitaxial graphene films on SiC with different stacking orders and twisting, as well as in the presence of intercalated hydrogen, we find that the interfacial transverse shear modulus is critically controlled by the stacking order and the atomic layer–substrate interaction. Importantly, we demonstrate that this modulus is a pivotal measurable property to control and predict sliding friction in supported two-dimensional materials. The experiments demonstrate a reciprocal relationship between friction force per unit contact area and interfacial shear modulus. The same relationship emerges from simulations with simple friction models, where the atomic layer–substrate interaction controls the shear stiffness and therefore the resulting friction dissipation.

了解原子层与其基底之间的界面特性是基础和技术层面的关键兴趣。从费米能级钉扎到应变工程和超润滑，单个原子层与其基底之间的相互作用决定着电子、机械和化学特性。在这里，我们测量了基板上原子层难以接近的界面横向剪切模量。通过对具有不同堆叠顺序和扭曲的 SiC 上的块状石墨和外延石墨烯薄膜以及存在插层氢的情况进行测量，我们发现界面横向剪切模量受堆叠顺序和原子层的严格控制–底物相互作用。重要的，我们证明该模量是控制和预测支撑二维材料滑动摩擦的关键可测量属性。实验证明了每单位接触面积的摩擦力与界面剪切模量之间的倒数关系。同样的关系也出现在简单摩擦模型的模拟中，其中原子层-基底相互作用控制剪切刚度，从而控制由此产生的摩擦耗散。