Complex magnetic energy landscapes in topological magnets

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Magnetic topology visuals
(a) Magnetic structure of TbMn6Sn6 showing the key Mn-Mn and Mn-Tb interlayer interactions. (b) Inelastic neutron scattering data showing selected spin wave branches compared to model calculations (pink lines).
Scientific Achievement

Inelastic neutron scattering measurements and first-principles calculations reveal a hierarchy of competing magnetic energy scales in the RMn6Sn6 (R=rare earth) family of kagome-lattice-based topological magnets.

Significance and Impact

Understanding the fundamental magnetic interactions  enables prediction of a material’s topological phase, such as a Weyl semimetal or Chern insulator, and reveals opportunities to tune its magnetism and topology.  

Research Details
  • The Chern insulator TbMn6Sn6 has ferromagnetic Mn kagome and Tb triangular layers with staggered magnetization. 
  • The spin wave spectrum of TbMn6Sn6 was measured on the ARCS instrument at the Spallation Neutron Source.
  • The discovery of long-ranged and competing interlayer interactions provide opportunities for magnetic tunability.
  • Density-functional theory calculations indicate that  principal interactions are transferrable across the RMn6Sn6 series.

S. X. M. Riberolles, Tyler J. Slade, D. L. Abernathy, G. E. Granroth, Bing Li, Y. Lee, P. C. Canfield, B. G. Ueland, Liqin Ke, and R. J. McQueeney, "Low-Temperature Competing Magnetic Energy Scalesin the Topological FerrimagnetTbMn6Sn6," Phys. Rev X 12, 021043 (2022).

Work performed at the Ames Laboratory used the Spallation Neutron Source and the National Energy Research Scientific Computing Center.