The Science
Scientists have developed a new method called Coherent Correlation Imaging to directly produce images of the changing structure in magnetic materials. This structure is a central component in many next-generation computing devices. The method can deliver information about a device in real time and with high spatial resolution. This allowed the researchers to observe features called domain walls by keeping track of their evolution for the first time. Domain walls are the boundaries between distinct magnetic regions in a material. Together, these domain walls contribute to a material's overall magnetic behavior. The results of this study show that some domains barely move while others shift continuously. It also shows how the domains make those shifts.
The Impact
Magnetic materials are essential for computers, cell phones, televisions, and many other electronic devices. To improve these materials, scientists need to study them in new and more effective ways. The novel imaging technique described here does just that. It allows researchers to observe a magnetic material at the nanoscale-the billionth of a meter level-over time by keeping track of its changing magnetic structure. This information will ultimately help to advance technologies that are based on harnessing the magnetic properties of materials.
Summary
Researchers developed a technique called Coherent Correlation Imaging (CCI) to image the evolution of magnetic domains in time and space, showing how the boundaries of some domains shift, while others barely move. This is due to a property called "pinning." While pinning is a known property of magnetic materials, the team directly imaged, for the first time, how pinning sites affect the motion of interconnected domain walls. The team took measurements at the National Synchrotron Light Source II, a Department of Energy Office of Science user facility at Brookhaven National Laboratory.
The algorithm they developed allowed them to categorize the images and reconstruct a movie of the domain movement. This movie then enabled them to connect the domain behavior to the pinning sites on the sample. This allowed them to map the pinning sites with unprecedented space and time combined resolution. This study is an important step to understanding how to manipulate magnetic domains for future applications. It also demonstrates CCI's usefulness beyond magnetic materials, since the technique can be transferred to different research areas, measurement techniques, and types of electronic order.
Funding
Funding for this research was provided by the Defense Advanced Research Projects Agency's Topological Excitations in Electronics program, the Leibniz Collaborative Excellence program, and the Helmholtz Young Investigator Group Program. This research used resources of the National Synchrotron Light Source II, a DOE Office of Science user facility.