The advances in the growth techniques provide numerous scope to explore the possibilities of new 2D materials for potential applications. With the aid of first-principle calculations we show that 2D Na can be a new addition to the family of thermodynamically stable 2D materials for device applications. Not surprisingly, due to half-occupied $3s$ orbital 2D Na possesses the features of the 2D electron gas (2DEG). The transport properties are examined based on the accurate solution of Boltzmann transport equation. With practically tunable carrier density in 2D materials, the intrinsic electrical resistivity of electron doped 2D Na is $\sim$ 1.4 times larger than that of graphene and falls below the latter 450 K onwards. The Bloch-Grüneisen temperature is almost constant at 50 K, independent of the type or density of the charge carriers. The electronic thermal conductivity of pure 2D Na is $\sim$ 1.24 times larger than that of its bulk counterpart at 300 K. The Wiedemann-Franz law stands tall in 2D Na with calculated Lorenz number 2.41 $\times 10^{-8} V^2/deg^2$ at room temperature. The transport mechanism presented here is expected to occur in all Na like systems with a clean Fermi surface.
Meyer等人（2007）发现，只有一个原子厚的独立石墨烯片显示出自发的波纹。波纹的数量级为2-20厘米高，20-200厘米宽。它们出现的薄片只有一个原子厚，通过支撑它们的金属支柱之间的真空延伸约5000埃。此后，其他研究小组也创造了独立的石墨烯（Garcia-Sanchez 2008 ; Bolotin et al. 2008），并在玻璃基板上发现了石墨烯的类似波纹（Geringer et al. 2008）。在这里，我们表明，这些波纹可以解释为吸附分子坐在随机网站的后果。被吸附物使碳原子间的键稍微变长。然后，静态吸附是由导致叶片弯曲的机制引起的;吸附物覆盖率约为20%所引起的吸附与实验观察一致。我们解释了为什么这种机制更有可能解释波纹比热波动或Mermin-Wagner定理，这是以前被调用。
Van der Waals heteroepitaxy of air stable quasi-free standing silicene layers on CVD epitaxial graphene/6H-SiC
石墨烯由具有原子级平坦的无悬挂键表面的惰性热稳定材料组成，本质上是用于二维材料如硅烯的范德华异质外延的理想模板层。然而，取决于合成方法和生长参数，石墨烯（Gr）衬底可以在单个样品上表现出各种表面结构、厚度、缺陷和台阶高度。这些结构显著地影响外延层的生长模式，例如将逐层生长转变为缺陷辅助成核促进的Volmer-Weber生长。本文采用原子力显微镜（AFM）、扫描隧道显微镜（STM）、X射线光电子能谱学（XPS）、扫描电子显微镜（SEM）和拉曼光谱（Raman）研究了在6 H-SiC（0001）衬底上化学气相沉积外延Gr（1 ML Gr/1 ML Gr缓冲层）上硅的生长。它示出，全尺寸几乎无缺陷的1 ML Gr与单一表面结构和分子束外延（MBE）沉积硅的超清洁条件的完美控制代表确保外延石墨烯上的扩展硅烯片的生长的关键先决条件。
Non-monotonic hydration dependence of ionic transport in atomically-thin MnO2 sheets
Institute of Materials Science and Nanotechnology, Bilkent University（比尔肯特大学材料科学与纳米技术研究所）；Bilkent National Nanotechnology Research Center - UNAM（比尔肯特国家纳米技术研究中心）；Department of Physics, Middle East Technical University（中东理工大学物理系）
