Most systems have more than two stable crystalline states in the phase diagram, which is known as polymorphism. Crystallization in such a system is often under strong influence of competing orderings linked to those crystals. However, how such competition affects crystal nucleation and ordering toward the final crystalline state is largely unknown. This is primarily because the competition takes place locally and thus is masked by large positional fluctuations. We develop a unique method to correctly identify local symmetries by removing their distortions due to positional fluctuations. This allows us to experimentally access the spatiotemporal fluctuations of local symmetries at a single-particle level in crystallization of a charged colloidal system near the body-centered cubic–face-centered cubic border. Thus, we successfully reveal the crucial roles of competing ordering in the initial selection of polymorphs and the final grain boundary motion toward the most stable state from a microscopic perspective.

大多数体系在相图中都具有两种以上的稳定晶态，这称为多晶型现象。这种系统中的结晶通常受到与这些晶体相关的竞争有序的强烈影响。然而，这种竞争如何影响晶体成核和最终晶态的有序化在很大程度上尚不清楚。这主要是因为竞争是在本地进行的，因此被巨大的位置波动所掩盖。我们开发了一种独特的方法，通过消除位置波动造成的扭曲来正确识别局部对称性。这使我们能够通过实验获得体心立方-面心立方边界附近带电胶体系统结晶过程中单粒子水平上局部对称性的时空涨落。因此，我们成功地从微观角度揭示了竞争排序在多晶型物的初始选择和最终晶界运动向最稳定状态的过程中的关键作用。