Cool a material to sufficiently low temperatures and it will seek some form of collective order. Add quantum mechanics or confine the geometry and the states of matter that emerge can be exotic, including electrons whose spins arrange themselves in spirals, pinwheels, or crystals.
In a recent pair of publications in Nature Communications, teams led by Caltech's Thomas F. Rosenbaum, professor of physics and holder of the Sonja and William Davidow Presidential Chair, report how they have combined magnetic fields and large pressures to not only induce these states at ultra-low temperatures, but also to nudge them between competing types of quantum order.
Rosenbaum is an expert on the quantum mechanical nature of materials—the physics of electronic, magnetic, and optical materials at the atomic level—that are best observed at temperatures near absolute zero. In the first of the two papers, published in June and led by Sara Haravifard, now on the faculty at Duke University, the team squeezed a collection of magnetic quantum particles in a pressure cell at temperatures near absolute zero and at magnetic fields more than 50,000 times stronger than the earth's field, and discovered the formation of new types of crystal patterns. The geometry of these crystal patterns not only reveals the underlying quantum mechanics of the interactions between the magnetic particles, but also bears on the kinds of collective states allowed for atomic systems, such as those that flow without friction.
To read more, click here.