Li Xiaowen, Qiang Xiaobin, Gong Zhenhao, Zhang Yubo, Gong Penglai, Chen Lang
Department of Physics, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China.
Research (Wash D C). 2021 Apr 10;2021:1904839. doi: 10.34133/2021/1904839. eCollection 2021.
Negative Poisson's ratio (NPR) materials are functional and mechanical metamaterials that shrink (expand) longitudinally after being compressed (stretched) laterally. By using first-principles calculations, we found that Poisson's ratio can be tuned from near zero to negative by different stacking modes in van der Waals (vdW) graphene/hexagonal boron nitride (G/-BN) superlattice. We attribute the NPR effect to the interaction of orbitals between the interfacial layers. Furthermore, a parameter calculated by analyzing the electronic band structure, namely, distance-dependent hopping integral, is used to describe the intensity of this interaction. We believe that this mechanism is not only applicable to G/-BN superlattice but can also explain and predict the NPR effect in other vdW layered superlattices. Therefore, the NPR phenomenon, which was relatively rare in 3D and 2D materials, can be realized in the vdW superlattices by different stacking orders. The combinations of tunable NPRs with the excellent electrical/optical properties of 2D vdW superlattices will pave a novel avenue to a wide range of multifunctional applications.
负泊松比（NPR）材料是功能性和机械性超材料，在横向压缩（拉伸）后会纵向收缩（膨胀）。通过第一性原理计算，我们发现通过范德华（vdW）石墨烯/六方氮化硼（G/ -BN）超晶格中的不同堆叠模式，泊松比可以从接近零调谐到负值。我们将NPR效应归因于界面层之间的轨道相互作用。此外，通过分析电子能带结构计算得到的一个参数，即距离相关的跳跃积分，用于描述这种相互作用的强度。我们认为这种机制不仅适用于G/ -BN超晶格，还可以解释和预测其他vdW层状超晶格中的NPR效应。因此，在三维和二维材料中相对罕见的NPR现象，可以通过不同的堆叠顺序在vdW超晶格中实现。可调谐的NPR与二维vdW超晶格优异的电学/光学性质的结合，将为广泛的多功能应用开辟一条新途径。
