A team at the University of Vienna, led by Kimmo Mustonen, encapsulates a monolayer of silver iodide between two graphene sheets to stabilize it and prevent it from collapsing into a three-dimensional phase, and films the entire atom-by-atom melting process via scanning transmission electron microscopy at over 1100°C, analyzing the data with convolutional neural networks. The experiment confirms for the first time the existence of the hexatic phase — predicted in 1979 by Halperin and Nelson — in a covalently bonded material, extending the range of systems where this state of matter has been observed beyond the liquid crystals, colloids, and electrons on liquid helium studied previously. The most surprising finding partially contradicts the original theoretical prediction: instead of two gradual, continuous transitions, the researchers observe that the solid-to-hexatic step is gradual, but the final hexatic-to-liquid step occurs abruptly, revealing that the two-dimensional melting mechanism in strongly bonded materials is more complex than the original KTHNY theory predicted.