Nanoscale Spin Dynamics Group

Hard-disk drives in personal computers and data centers push the limits of technology, with current data bit densities of 100 billion per square centimeter. The controlled switching of magnetization in write heads, read heads, recording media, and innovative memory elements at frequencies in the hundreds of megahertz to hundreds of gigahertz will be the foundation for future magnetic data storage systems and advanced microwave integrated circuits. These technologies will depend on newly discovered properties and limitations of magnetic materials and devices that appear only at the nanoscale.

We will develop coherent X-ray scattering techniques that will enable room-temperature detection and characterization of magnetic topological defects (skyrmions) at length scales as small as 5 nm. The new method will rely on optical generation of skyrmions via the Kibble-Zurek mechanism, whereby rapid cooling of a magnet through the Curie temperature after optical pumping will necessarily generate topological defects. Detection of skyrmions will rest on the distinct diffractive fingerprint of the scattered photons. Analysis of the diffraction pattern will be used to determine the skyrmion size and density. We will use both coherent X-ray and extreme ultraviolet laser facilities for these measurements, including those of our long-time collaborators at University of ColoradoCU/JILA. Results of these measurements will be crucial for the evaluation of materials as candidates for spintronics applications, including racetrack memory and logic-in-memory.