Interfacial energetics of two-dimensional colloidal clusters generated with a tunable anharmonic interaction potential
Interfacial energetics of two-dimensional colloidal clusters generated with a tunable anharmonic interaction potential
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DOI：
10.1103/physrevmaterials.2.025602
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发表时间：
2018-02-07
影响因子：
3.4
通讯作者：
Biswal, Sibani Lisa
中科院分区：
文献类型：
--
作者：
Hilou, Elaa;Du, Di;Biswal, Sibani Lisa
界面特性对二维（2D）材料的各种性质至关重要，例如异质结的能带对准和二维晶体的成核动力学。尽管人们希望利用这些增强的界面特性来设计新材料，但意想不到的相变和2D形态特有的缺陷，留下了许多悬而未决的问题。特别是，构型各向异性的影响，这是很难分离的实验，它们对界面性质的影响还没有很好的理解。在这项工作中，我们开始探索这种结构-热力学关系，使用旋转磁场在二维顺磁粒子系统中产生非调和相互作用势。在低磁场强度下，弱相互作用的胶体颗粒形成非紧密排列的流体状液滴，而在高磁场强度下，观察到具有六方有序的晶体。我们通过测量局部键取向、顺序参数和界面刚度作为相互作用强度的函数来研究这些二维胶体团的空间和界面性质。据我们所知，这是第一个通过使用外场控制粒子相互作用来测量二维胶体团的可调界面刚度的研究。
Interfacial characteristics are critical to various properties of two-dimensional (2D) materials such as band alignment at a heterojunction and nucleation kinetics in a 2D crystal. Despite the desire to harness these enhanced interfacial properties for engineering new materials, unexpected phase transitions and defects, unique to the 2D morphology, have left a number of open questions. In particular, the effects of configurational anisotropy, which are difficult to isolate experimentally, and their influence on interfacial properties are not well understood. In this work, we begin to probe this structure-thermodynamic relationship, using a rotating magnetic field to generate an anharmonic interaction potential in a 2D system of paramagnetic particles. At low magnetic field strengths, weakly interacting colloidal particles form non-close-packed, fluidlike droplets, whereas, at higher field strengths, crystallites with hexagonal ordering are observed. We examine spatial and interfacial properties of these 2D colloidal clusters by measuring the local bond orientation order parameter and interfacial stiffness as a function of the interaction strength. To our knowledge, this is the first study to measure the tunable interfacial stiffness of a 2D colloidal cluster by controlling particle interactions using external fields.