New State of Matter: Crystalline and Flowing at the Same Time

Cluster crystals consist of a core of organic polymers surrounded by DNA molecules ( right ). Pressed together ( left ), they exhibit properties of crystals and liquids at the same time. Natasa Adzic, University of Vienna) - Through their research efforts, the team was able to finally disprove an intuitive assumption that in order for two particles of matter to merge and form larger units (i.e. aggregates or clusters), they must be attracted to each other. As early as the turn of the century, a team of soft matter physicists headed by Christos Likos of the University of Vienna predicted on the basis of theoretical considerations that this does not necessarily have to be the case. They suggested that purely repulsive particles could also form clusters, provided they are fully overlapping and that their repulsion fulfils certain mathematical criteria. Since then, further theoretical and computational work has demonstrated that if compressed under external pressure, such clusters develop crystalline order in a way similar to conventional materials such as copper and aluminium.