Brillouin light scattering (BLS), an inelastic light scattering technique, has been used for decades to study phonons and magnons, also known as spin waves, in a wide range of materials. The BLS technique has proven to be a useful tool to investigate spin wave dynamics in continuous thin films and it has also been used to explore driven spin wave processes in low-damping yttrium iron garnet (YIG) films where the spin waves propagate for distances over several millimeters. In both cases, spatial resolutions of a few tens of micrometers are sufficient to resolve the dynamics. Within the past few years, advancements in the BLS technique have included the development of micro-BLS and with this new technique spatial mapping of spin dynamics on sub-micrometer length scales can now be realized. This talk will cover BLS measurements of thermally excited magnons in Fe65Co35 and parametrically excited magnons in YIG. A set of continuous Fe65Co35 thin films, a high-magnetization alloy that is used in magnetic read/write heads, were studied to determine the exchange constant for this material and time and space resolved-BLS measurements were conducted on YIG to determine the group velocities of magnons formed by nonlinear three magnon splitting and confluence processes. The development of micro-BLS and the measurements of confined spins waves in patterned Permalloy nanostructures will also be discussed.
Department of Physics, Colorado State University, Fort Collins, Colorado