Newly discovered magnetic interactions in Kagome’s topological layered magnet TbMn6Sn6 could hold the key to customizing how electrons flow through these materials. Scientists from the US Department of Energy’s Ames National Laboratory and the Oak Ridge National Laboratory conducted an extensive investigation of TbMn6Sn6 to better understand the material and its magnetic characteristics. These results could have an effect on future technological advances in areas such as quantum computing, magnetic storage media and high-precision sensors.
Kagomes are a kind of material whose composition takes its name from a traditional Japanese technique of weaving baskets. The weaving produces a pattern of hexagons surrounded by triangles and vice versa. The arrangement of atoms in Kagome metals replicates the weaving pattern. This characteristic causes the electrons in the material to behave in an exclusive way.
Solid materials have electronic properties controlled by the characteristics of their electronic band construction. The band structure is highly dependent on the geometry of the atomic lattice, and sometimes the bands can display special shapes such as cones. These particular shapes, called topological features, are responsible for the unique behavior of electrons in these materials. The Kagome structure in particular leads to complex and potentially tunable features in electronic bands.
The use of magnetic atoms to build the lattice of these materials, such as Mn in TbMn6Sn6, may further help induce topological features. Rob McQueeney, Ames Lab scientist and project leader, explained that topological materials “have a special property where under the influence of magnetism you can get currents flowing around the edge of the material, which are non-dissipating, that which means that the electrons do not scatter and they do not dissipate energy.”
The team set out to better understand the magnetism in TbMn6Sn6 and used calculations and neutron scattering data collected from the Oak Ridge spallation neutron supply to perform its analysis. Simon Riberolles, postdoctoral research associate at Ames Lab and member of the project team, explained the experimental approach used by the team. The procedure involves a neutron particle beam which is used to test the rigidity of the magnetic order. “The nature and drive of different magnetic interactions present in materials can all be mapped using this technique,” he said.
They have discovered that TbMn6Sn6 has competing interactions between the layers, or what is called frustrated magnetism. “So the system has to compromise,” McQueeney said, “usually that means if you push it, you can make it do different things. But what we discovered in this material is that even if these competitors there are interactions, there are other interactions that are dominant.”
It This is the first detailed study of the magnetic properties of TbMn6Sn6 to be published. “In research. or that you are measuring something that has not been seen before, or that has been understood partially or in a different way,” Riberolles said.
McQueeney and Riberolles explained that their findings suggest that the material could potentially be tuned for specific magnetic characteristics, for example by changing the Tb for a different uncommon earth element , which would change the magnetism of the compound. This basic research paves the way for further advances in Kagome metal discovery.
This research is discussed in more detail in the article “Very low-temperature level of competition magnetic vitality scales in the topological ferrimagnet TbMn6Sn6,” by SXM Riberolles, TJ Slade, DL Abernathy, GE Granroth, B. Li, Y. Lee, Laptop Canfield, BG Ueland, L. Ke and RJ McQueeney and published in Physical Critique X.