Student Spotlight: Sargent-Glover Uses Near-Field Spectroscopy to Investigate Domain Walls
Ashley Sargent-Glover, 4th year PhD student in the Department of Chemistry, recently co-authored a publication in the Journal of Applied Physics. Sargent-Glover, and a team of researchers from the University of Tennessee, Knoxville and Rutgers University used near-field spectroscopy and phonon lifetime calculations to examine the relationship between material structure and properties.
Sargent-Glover’s work focuses on using synchrotron-based near-field spectroscopy to investigate domain walls. Domain walls form in materials where there are slight variations in the crystal structure, and serve as boundaries between regions, or domains, of materials. Domain walls are an increasingly important area of exploration due to their potential in the development of low-energy electronic and memory storage devices.
“Near-field spectroscopy is unique because it is a tip-based technique. What that means is we are able to focus the light from our instrument so tightly that we can get down to 20 nanometer resolutions, whereas traditional far-field instruments are stuck at around 2 to 10 microns. Near-field spectroscopy has been crucial to my work examining domain walls,” said Sargent-Glover.
Her recent publication used nickel tellurium oxide (Ni3TeO6) as a means of exploring where the material’s properties come from. This material was particularly useful as it contains both polar and chiral domains, and both charged and neutral interfaces. This allowed Sargent-Glover and her fellow researchers to investigate the relationships between a variety of structures and material properties, and identify trends in those relationships.
Among these trends, they found that charged domain walls are twice as wide as neutral walls due to the added strain caused by the positioning of the chiral helix. They also determined that neutral domain walls require less energy to form than charged domain walls. These findings contribute to the fundamental knowledge needed to effectively leverage domain walls for future applications, such as electronic device development.
The research for this publication was one of the first uses of phonon lifetime calculations for analyzing domain wall properties. It also employed a new beam line end station at the National Synchrotron Light Source at Brookhaven National Laboratory, which Sargent-Glover was the first to use.
“Not many groups are using this technique and we’re still learning so much about its capabilities,” said Sargent-Glover. “Not only does this research contribute to micro-electronics and domain wall physics, it also contributes to the understanding of how this instrumentation can be leveraged, and I think that’s going to be really important moving forward.”
The publication, “Near-field infrared imaging of polar domain walls in Ni3TeO6,” features the work of an interdisciplinary team of UT researchers from the Department of Chemistry and the Department of Physics and Astronomy. External collaborators included researchers from the Keck Center for Quantum Magnetism and the Department of Physics and Astronomy at Rutgers University, and the National Synchrotron Light Source II at Brookhaven National Laboratory.