Illustration of ultracold fermionic atoms in an optical lattice potential. Along the strong bonds of the lattice, antiferromagnetic (or anti-aligning) correlations form, detection of which has only now been achieved, allowing for a better understanding of the signature of quantum magnetism. Credit: Thomas Uehlinger, ETH Zürich
Physicists understand perfectly well why a fridge magnet sticks to certain metallic surfaces. But there are more exotic forms of magnetism whose properties remain unclear, despite decades of intense research. An important step towards filling these gaps comes now from Tilman Esslinger and his group at the Department of Physics.
The team has developed a new kind of device that uses laser beams and atoms to emulate magnetic materials. Their approach promises fundamental insights beyond what can be obtained with current theoretical and computational methods. Moreover, the work might guide researchers towards finding new materials with interesting properties for future technologies and applications.
The concert of tiny magnets – Magnetic materials owe their properties to the intricate interplay between a myriad of tiny magnets. These elemental magnets come typically in the form of individual electrons, each of which is weakly magnetic. Observable magnetism arises when these magnetic building blocks are arranged in specific patterns, in which they are held by quantum-mechanical interactions. A typical fridge magnet, for example, is composed of several ferromagnetic sections; in each segment all elemental magnets are aligned in parallel, giving rise to the known magnetic behaviour.
In other magnetic materials the situation is much more subtle, and the elemental magnets are arranged into more complicated patterns. Examples include so-called quantum spin liquids, where the elemental magnets interact in a way that prevents them from ever reaching an ordered state such as that found in a ferromagnet. Physicists and material scientists are interested in such unusual magnets as they are landmark problems in many-body quantum physics, but also because these materials possess properties that may be the basis of robust and compact magnetic data-storage devices or of novel forms of information processors. More here A quantum simulator for magnetic materials.