Spotight

Yan-Jiun Chen

Yan-Jiun Chen is a graduate student working with Professor Jim Sethna studying non-equilibrium statistical physics, in particular, the scaling properties of crackling noise in magnets.  As a magnet is magnetized, magnetic spins flip in avalanches of all different sizes, this is called the Barkhausen effect (or crackling noise). The properties of these avalanches exhibit self-similarity, and can be studied using powerful theoretical tools in the form of the renormalization group (RG).  This means that studying these avalanches can tell us about other systems that exhibit similar behavior (or in statistical physics terms: belong to the same universality class).

“Recent advances in optical imaging techniques have made more information about these avalanches available.  We have a collaborator that has new data on the spatial structure of avalanches in 2D.  To facilitate merging experiment with theory, we’ve developed software named SloppyScaling.  Just input your theory functions, and it automatically fits the theory to any data you give it”, Yan-Jiun says.  “This software is cool because it can also be applied to a wide range of problems in statistical physics, not just magnetic avalanches, and it is flexible enough so that this is an easy task”

With this tool, they have also been exploring simulation data from different models, some of which describe magnetic avalanches.  They have discovered interesting questions about the behavior of these different models, and are working to come up with the right theoretical framework to tie these all together.