Dynamical fractal discovered in clean magnetic crystal
A new type of fractal has been discovered in a class of materials called spin ices—famous, among other reasons, for their emergent magnetic monopole excitations. Spin ice materials are some of the most researched and best understood topological magnets. Nevertheless, the unusual dynamical properties of spin ice have been puzzling scientists for almost two decades. An international research team, including Jonathan N. Hallén and Roderich Moessner of the Max Planck Institute for the Physics of Complex Systems, has now shown that the dynamical rules governing the motion of the magnetic monopoles constrain these to move on fractal structures. By hosting the monopole motion, the fractals cause the peculiar dynamical behaviours observed in spin ice materials.
The discovery was surprising because the fractals were seen in a clean three-dimensional crystal, where they would not be expected conventionally. Even more remarkably, the fractals are visible in dynamical properties of the crystal, and hidden in static ones. The capacity of spin ice to exhibit such striking phenomena makes the team hopeful that spin ice will allow further surprising discoveries in the cooperative dynamics of even simple topological many-body systems.
More details can be found in a press release (PDF).