Akutsu Noriko
Faculty of Engineering, Osaka Electro-Communication University, Hatsu-cho, Neyagawa, Osaka, 572-8530, Japan.
Sci Rep. 2023 Sep 26;13(1):16086. doi: 10.1038/s41598-023-43002-3.
The roughness of crystal surfaces and the shape of crystals play important roles in multiscale phenomena. For example, the roughness of the crystal surface affects the frictional and optical properties of materials such as ice or silica. Theoretical studies on crystal surfaces based on the symmetry principle proposed that the growing surfaces of crystal growth could be classified in the universal class of Kardar-Parisi-Zhang (KPZ), but experiments rarely observe KPZ properties. To fill this the gap, extensive numerical calculations of the crystal growth rates and the surface roughness (surface width) have been performed for a nanoscale lattice model using the Monte Carlo method. The results indicate that a (001) surface is smooth within the single nucleation growth region. In contrast, the same surface is atomically smooth but thermodynamically rough in the poly-nucleation growth region in conjunction with a KPZ roughness exponent. Inclined surfaces are known to become Berezinskii-Kosterlitz-Thouless (BKT) rough surfaces both at and near equilibrium. The two types of steps associated with the (001) and (111) terraces were found to induce KPZ surface roughness, while the interplay between steps and multilayered islands promoted BKT roughness.
晶体表面的粗糙度和晶体形状在多尺度现象中起着重要作用。例如，晶体表面的粗糙度会影响冰或二氧化硅等材料的摩擦和光学性质。基于对称原理对晶体表面进行的理论研究表明，晶体生长的生长表面可归类于 Kardar-Parisi-Zhang（KPZ）普适类，但实验中很少观察到 KPZ 特性。为了填补这一空白，使用蒙特卡罗方法对纳米尺度晶格模型进行了大量关于晶体生长速率和表面粗糙度（表面宽度）的数值计算。结果表明，（001）表面在单核生长区域内是光滑的。相比之下，同一表面在多核生长区域内原子上是光滑的，但结合 KPZ 粗糙度指数在热力学上是粗糙的。已知倾斜表面在平衡态及接近平衡态时都会变成 Berezinskii-Kosterlitz-Thouless（BKT）粗糙表面。发现与（001）和（111）平台相关的两种类型的台阶会导致 KPZ 表面粗糙度，而台阶与多层岛之间的相互作用促进了 BKT 粗糙度。
