Homepage for UWB Portal News

When ice turns into water, it is a familiar process from everyday life. But what happens when a crystal, only a few atoms thick, turns into a liquid? This question is addressed by a scientific paper by an international team of physicists published in Science at the end of the year.

The researchers described and directly observed, for the first time, the existence of the so-called hexatic phase in an ultra-thin layer of silver iodide. The hexatic phase is a transitional state between a solid and a liquid that exists only in two dimensions. “Imagine a military formation beginning to fall apart. The soldiers no longer keep precise spacing in their ranks and lose their regular order, but they all still face the same direction and maintain their orientation. That is the hexatic phase. It exists only briefly, within a narrow temperature window just before complete melting,” explained Viera Skákalová.

To capture this phenomenon, the team used a unique experimental method in which silver iodide crystals were encapsulated between layers of graphene, and their transformation was monitored using state-of-the-art electron microscopes with atomic resolution. “The discovery of a new phase of matter in two-dimensional crystals opens the way to precisely controlling and tuning the properties of ultra-thin materials,” Skákalová explained. According to her, this enables the development of faster, more energy-efficient, and flexible electronics, as well as highly sensitive sensors and new energy technologies that would not be possible without understanding how these materials behave during the transition between solid and liquid states.

The publication in Science represents a historic milestone for the NTC at the University of West Bohemia in Pilsen. “This is the first paper co-authored by NTC to be published in Science. It confirms that our strategy of focusing on top-level research in quantum materials is bearing fruit and that we belong among the world’s leading research institutions,” said Petr Kavalíř, Director of the NTC Research Centre. In addition to the University of West Bohemia in Pilsen, the study involved researchers from leading scientific institutions in Austria, Germany, Belgium, Poland, and Slovakia.

Link to the publication in Science: https://www.science.org/doi/10.1126/science.adv7915