Researchers have observed magnetic excitations that mimic the properties of an axion particle in a collaborative effort including the U.S. Department of Energy Ames National Laboratory and led by Harvard University. The axion is a particle that has been theorized to explain the dark matter that exists throughout the universe. A discovery like this one has the potential to solve several mysteries in quantum field theory and may even be used to detect real axions in the universe.
In addition to the scientific importance of finding the axion, the discovery is also a milestone achievement for the Center for the Advancement of Topological Semimetals (CATS), an Energy Frontier Research Center (EFRC) funded by the U.S. Department of Energy, Office of Basic Energy Sciences.
“When the CATS EFRC was renewed in 2022, this was a major objective that we set, because we felt like we had the right material to see it,” said Robert McQueeney, director of the CATS and a scientist at Ames Lab.
The axion quasiparticle is created by generating magnetic excitations in a magnetic 2D material, manganese, bismuth-two, tellurium-four (MnBi2Te4) using laser pulses. McQueeney is an expert in this compound’s magnetic properties and unique magnetic excitations called magnons. His knowledge of the material and its behavior was instrumental in the discovery.
“I utilized my knowledge of the magnetism of this system, to help [the team] to understand the data they were seeing,” said McQueeney. “We wanted to make sure that when they did these probe experiments, they were in fact measuring magnons, and that the frequencies that they were observing were consistent with the models that we had developed.”
McQueeney explained that there are two incarnations of axions. One has been hypothesized as one of the leading candidates for dark matter. The second is something that can be generated in a condensed matter system, which is like a small laboratory to create quasiparticles.
“This CATS project was led by Harvard, but it was a collaboration with multiple CATS institutions and PIs. So it was really a big collaborative effort, and it shows what science can accomplish through teamwork.”
Learn more about the research from the Harvard Gazette.
This research is further discussed in: “Observation of the axion quasiparticle in 2D MnBi2Te4,” written by Jian-Xiang Qiu, Barun Ghosh, Jan Schütte-Engel, Tiema Qian, Michael Smith, Yueh-Ting Yao, Junyeong Ahn, Yu-Fei Liu, Anyuan Gao, Christian Tzschaschel, Houchen Li, Ioannis Petrides, Damien Bérubé, Thao Dinh, Tianye Huang, Olivia Liebman, Emily M. Been, Joanna M. Blawat, Kenji Watanabe, Takashi Taniguchi, Kin Chung Fong, Hsin Lin, Peter P. Orth, Prineha Narang, Claudia Felser, Tay-Rong Chang, Ross McDonald, Robert J. McQueeney, Arun Bansil, Ivar Martin, Ni Ni, Qiong Ma, David J. E. Marsh, Ashvin Vishwanath, and Su-Yang Xu, and published in Nature.
Work for this research was partly supported by the Center for the Advancement of Topological Semimetals (CATS), an Energy Frontier Research Center funded by the U.S. DOE, Office of Basic Energy Sciences and led by Ames National Laboratory.
Ames National Laboratory is a U.S. Department of Energy Office of Science National Laboratory operated by Iowa State University. Ames Laboratory creates innovative materials, technologies, and energy solutions. We use our expertise, unique capabilities, and interdisciplinary collaborations to solve global problems.
Ames Laboratory is supported by the Office of Science of the U.S. Department of Energy. The Office of Science is the single largest supporter of basic research in the physical sciences in the United States and is working to address some of the most pressing challenges of our time. For more information, please visit https://energy.gov/science.