Hexatic phase in covalent two-dimensional silver iodide
- Thuy An Bui
- David Lamprecht
- Jacob Madsen
- Marcin Kurpas
- Peter Kotrusz
- Alexander Markevich
- Clemens Mangler
- Jani Kotakoski
- Lado Filipovic
- Jannik C. Meyer
- Timothy J. Pennycook
- Viera Skákalová
- Kimmo Mustonen
2025-12-04
According to the Kosterlitz-Thouless-Halperin-Nelson-Young (KTHNY) theory, the transition from a solid to liquid in two dimensions proceeds through an orientationally ordered liquid-like hexatic phase. However, alternative mixed melting scenarios, in which melting proceeds through the hexatic phase with both continuous and discontinuous transitions, have also been observed in some two-dimensional systems. In this study, we imaged silver iodide embedded in multilayer graphene using time- and temperature-resolved in situ atomic-resolution scanning transmission electron microscopy and nanobeam electron diffraction. We observed the hexatic phase and provide evidence supporting a mixed melting scenario.