Topological phases in 2D Kagome magnets

The Kagome lattice is a 2D network of corner-sharing triangles, which by symmetry is expected to host Dirac fermions and a non-trivial flat band. Initial research on magnetic Kagome materials was directed towards frustration-driven spin-liquid phases, potentially hosting Majorana quasiparticles. More recent theoretical efforts address topological order and emergent electronic excitations, such as the anomalous and fractional quantum Hall effects and Weyl fermions (1-3), engendered by the combination of the lattice symmetry with spin-orbit coupling and magnetic order.

One focus of our research is to study the topological electronic phases and the underlying magnetic order in 2D Kagome magnets. Thin films of the 2D Kagome magnet FeSn, suitable for STM experiments, can be synthesized by in-situ epitaxial growth down to the single layer limit (4, 5). The combination of spin-sensitive measurements with quasiparticle interference mapping with an STM presents exciting avenues to visualize the spin-ordered ground states atomically resolved, and to characterize the electronic structure and topological band gaps. For this purpose we are currently developing state-of-the-art low-temperature STM instrumentation that allows for the in-situ growth and characterization of epitaxial thin films of FeSe and related compounds.

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(4) Appl. Phys. Lett. 115, 072403 (2019)
(5) Nature Materials 19, 163-169 (2020)