[Seminar] "Symmetry and topology in tripod kagome magnets" by Dr. Owen Benton

The kagome lattice is a network of corner sharing triangles. Placing magnetic ions on this lattice renders it impossible for them to satisfy all their mutual interactions, leading to strong fluctuations and the possibility of unusual quantum ground states. Recently, a new class of kagome materials, known as “tripod kagome’’ magnets, has been discovered in which the physics is enriched further by strong spin-orbit coupling, leading to highly anisotropic interactions. Here, I present a theory of this new kind of magnetic material.

I will show that even though the microscopic exchange interactions are unavoidably complicated, much of the physics can be understood through consideration of the discrete point group symmetries of the kagome lattice. Using this approach, it is possible to determine a phase diagram, which explains experimental observations on several different tripod kagome materials. Particular attention will be paid to the material Mg₂Yb₃Sb₃O₁₄, for which the theory predicts the existence of excitations with a topologically nontrivial band structure. This makes Mg₂Yb₃Sb₃O₁₄ a potential realisation of a “topological magnon insulator”, a magnetic analog of topological insulators.