Clarke Safsten and Karine Chenel, Physics and Astronomy Department
My project for which I received an ORCA grant has advanced considerably. I work with Dr. Chesnel studying magnetic thin films. These films consist of layered ferromagnetic and antiferromagnetic materials. In previous experiments, Dr. Chesnel has determined that these types of films exhibit a property called magnetic memory. My project is to determine if the magnetic memory persists, and to what degree, in various circumstances. My project is divided into three primary pieces: experiment, computation, and conclusion.
Our experiment was conducted in July 2014. We traveled to Chicago, Illinois and worked at Argonne National Laboratory to perform measurements on these thin film samples. To be able to “see” the domain structure of these samples, we need to scatter coherent synchrotron radiation through the sample and measure the scattering pattern with a CCD camera.
Our setup included a magnet to expose the sample to an external field, a vacuum chamber because soft x-rays quickly absorbed by air, and a cryostat to cool the sample to about 20 K. I assisted in setting up the experiment and spent many hours during the week acquiring and logging data. During the week of the experiment, we acquired more than two thousand images from the CCD camera.
The next step is to analyze the images obtained in experiment in order to determine if the magnetic memory persists, and to what degree, in our experiments. The analysis is performed on software I wrote before the experiment began (with some final edits after). Some of the software was written by previous students, but I wrapped all of the pieces together and automated most of the process. To run the software on all two thousand images takes literally hundreds of computation hours, but I completed it and I now have results ready to be examined.
The results of the analysis are “maps,” or images showing how the magnetic memory is maintained as the external magnetic field changes. We are currently in the process of examining these images and drawing conclusions about the sample based on what we see. We do indeed see that magnetic memory persists in these samples, even in more abundance than expected in some circumstances. We are concerned, however, that some of the analysis steps need to be re-done because some of the results show unrealistic amounts of memory.
Moving forward, I will repeat parts of the analysis to get better results, and teach another student how to complete the analysis because I will be graduating soon. I will also detail my project and results in a Senior Thesis and a paper for publication.