Madalynn Marshall Selected for Department of Energy Graduate Student Research Program

Madalynn Marshall in lab

LSU Chemistry graduate student, Madalynn Marshall, was selected as one of the 49 U.S. graduate students to participate in the Department of Energy (DOE) Office of Science Graduate Student Research (SCGSR) Program for her project titled, “Neutron Study on Magnetic Topological Quantum Material Candidate EuMg₂Bi₂.” Madalynn works under the direction of Professor Weiwei Xie and will also be working under the direction of Dr. Huibo Cao while at Oak Ridge National Laboratory during her fellowship.

Quantum materials harnessing both topological electronic states and magnetism can open the door to new and advanced quantum technologies. However, unconventional synthetic techniques have held the production of these materials back. This research highlights the new magnetic topological quantum material candidate, EuMg₂Bi₂, which can be fabricated utilizing high temperature solid­state techniques as determined by Oak Ridge National Laboratory (ORNL). Based on previous data accomplished by ORNL using a physical property measurement system, EuMg₂Bi₂ showed an antiferromagnetic transition at around 8.2K. To further investigate the electronic behavior, ARPES data was performed in collaboration with Brookhaven National Laboratory (BNL) and confirmed the surface state of EuMg₂Bi₂ to be similar to the observed type II nodal­line semimetal Mg₃Bi₂ previously determined in our group. As a result, the HB-­3A Dimensional Extreme Magnetic Neutron Diffractometer (DEMAND) at the High Flux Isotope Reactor (HFIR) at ORNL will be used to perform an intensive neutron scattering study, which will determine the magnetic structure of EuMg2Bi2. The outcome will provide an understanding of the complex interplay between the topological and magnetic behavior in EuMg₂Bi₂.

crystal structure

Figure 1. (a) Image of the crystal structure of EuMg₂Bi₂ along the bc plane. (b) Calculated Wilson loop to determine Z₂ of EuMg₂Bi₂. (c) ARPES data for the electronic structure of EuMg₂Bi₂.

The SCGSR program provides funds for graduate awardees to conduct part of their thesis research at a host DOE laboratory in collaboration with a DOE laboratory scientist. The program advances graduate awardees’ overall doctoral work while providing access to the expertise, resources, and capabilities available at the DOE laboratories. For more additional program information, visit DOE SCGSR.

Dr. Weiwei Xie Research Group