This image of a quasicrystal lattice shows the uniquely symmetrical but never-repeating pattern of its components. The colors correspond to the orientation of the magnetic polarization of each edge. Image: Amanda Petford-Long/Argonne National Laboratory.Most materials, when viewed at the atomic level, come in one of two types. Some materials, like table salt, are highly crystalline, which means that the atoms in the material are arranged in orderly and repeating geometric patterns. Other materials, such as glass, display no such organization; in these materials, the atoms are arranged in what scientists call an amorphous structure.
A few special materials, however, straddle the line between crystalline and amorphous. These materials, known as quasicrystals, have atomic structures that are geometrically organized but, unlike those of crystalline materials, never repeat themselves. In a new study, scientists from the US Department of Energy's (DOE's) Argonne National Laboratory investigated networks of magnetic material patterned into the unique and quite beautiful geometries found in quasicrystals to see how the nature of the nonrepeating patterns leads to the emergence of unusual energetic effects. They report their findings in a paper in Scientific Reports.
The simple but elegant geometric patterns within a quasicrystal are reminiscent of a stained-glass window or a Buddhist mandala. "Quasicrystals are scientifically interesting because their internal organization creates effects that you don't see in other materials," said Argonne senior materials scientist Amanda Petford-Long, who led the study.
Just as different pieces of glass come together along their edges to create shapes and patterns in a stained-glass window, a quasicrystal contains junctions that define its behavior. Although the junctions in a quasicrystal can contain differing numbers of intersecting edges, each junction within a quasicrystal exhibits the same basic physical preference – to be in the lowest energy state possible. However, because each point within the quasicrystal is constantly interacting and competing with its neighbors, not all of the junctions can be in their lowest energy states at the same time.
In the experiment, the Argonne researchers wanted to see how the quasicrystal's structure responded to adding some extra energy. "We were looking at whether we could actually transfer energy from one side of the lattice to the other, and to image the patterns that emerged when we tried to do so," explained Argonne materials scientist Charudatta Phatak, another author of the study.
To their surprise, the researchers discovered that the redistribution of energy through the quasicrystal took place as a chain reaction that resembled the forked branches of a lightning strike. Unlike in a more conventional magnetic lattice, where these ‘avalanches’ of energy redistribution occur in only a single direction, the spread of redistributed energy throughout the quasicrystal lattice takes on a tree-like appearance.
This means that quasicrystals could be an example of a system that scientists have been looking for: a network made up of magnetic islands that can propagate and store information. According to Phatak, the behavior of these kinds of networks depends upon the amount of energy put into the system.
Understanding the energetic behaviors of these kinds of networks could be essential for developing next-generation computational devices. These devices could form the foundation for things like artificial neural networks, which would be able to perform complex computations with very low energy consumption.
This story is adapted from material from Argonne National Laboratory, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.