Signals ride on waves of one kind or another: light, sound, radio. But new carriers are needed to relay information in next-generation devices. Disturbances or waves in magnetic materials called magnons could be an efficient option - if scientists can tame them. A team led by researchers from the U.S. Department of Energy’s (DOE) Argonne National Laboratory and the University of Illinois Urbana-Champaign (U. of I.) has developed a method to generate spontaneous magnons in a material called yttrium iron garnet (YIG) that can be tuned to an external signal. The results, reported in Nature Communications, establish a pathway toward controllable magnons that are relevant for next-generation microelectronics, wireless communication and quantum information processing. Researchers know how to generate magnons in magnetic thin films. Less is known about how to make those oscillations both spontaneous, or self-sustaining, and steadily rhythmic in response to an external cue. Achieving stable magnons means a new way for delivering and processing information in ways that other types of waves cannot. “Parametric pumping usually creates chaotic wave motions, and it is hard to use the chaos for applications. With our method, we can create ultrasharp waves that are highly controllable.” - Yi Li, Argonne assistant scientist To achieve this goal, the magnons are generated using a technique called parametric pumping. Think about parametric pumping as a person on a swing: By timing their motion with the swing’s natural rhythm, they can add energy without an external push. A similar principle is used to drive magnons. The pumping method begins with a pair of microwave antennas on a YIG thin film a couple hundred nanometers thick, a tiny fraction of the width of a human hair. The small antenna dimensions enable scientists to control the generation of spontaneous oscillations with extreme precision. The magnons are then