Direct observation of phase transitions in Archimedean trunctated tetrahedrons under quasi-2D confinement

David Doan; John Kulikowski; X. Wendy Gu

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arXiv · 2308.02943

Direct observation of phase transitions in Archimedean trunctated tetrahedrons under quasi-2D confinement

David Doan·John Kulikowski·X. Wendy Gu

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Abstract

Colloidal crystals are used to understand fundamentals of atomic rearrangements in condensed matter and build complex metamaterials with unique functionalities. Simulations predict a multitude of self-assembled crystal structures from anisotropic colloids, but these shapes have been challenging to fabricate. Here, we use two-photon lithography to fabricate Archimedean truncated tetrahedrons and self-assemble them under quasi-2D confinement. Under a small gravitational potential, these particles self-assemble into a hexatic phase, which has not yet been observed or reported for this shape. Under additional gravitational potential, the hexatic phase transitions into a quasi-diamond two-unit basis. In-situ imaging reveal this phase transition is initiated by an out-of-plane rotation of a particle at a crystalline defect and causes a chain reaction of neighboring particle rotations. Our results provide a framework of studying different structures from hard-particle self-assembly and demonstrates the ability to use confinement to induce unusual phases.

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David Doan, John Kulikowski, X. Wendy Gu. 2023-08-05. Direct observation of phase transitions in Archimedean trunctated tetrahedrons under quasi-2D confinement. https://arxiv.org/abs/2308.02943

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