RIXS Shows Flat-Band Stoner Excitations in a Kagome Semimetal

A sensitive synchrotron technique uncovers exotic behaviour important to next-gen electronics

Topological materials (including topological insulators, Dirac and Weyl semimetals and skyrmions) are a hot topic in science at the moment. A gold rush of sorts is underway, to discover and investigate the exotic physical properties of these materials, which could be the key that unlocks next-generation energy-efficient electronic devices and quantum computing. In some materials, geometrical confinement of electrons can give rise to electronic correlations that manifest as dispersionless ‘flat’ bands. These flat bands are of particular interest, as they can result in unconventional ferromagnetic and transport behaviour. However, there have been few characterisations of flat bands and their magnetism. In work recently published in Nature Communications, scientists from Diamond’s I21 beamline used resonant inelastic X-ray scattering (RIXS) to investigate the ferromagnetic Kagome semimetal Co3Sn2S2, reporting the first observation of flat-band Stoner excitations in this material. Their results also demonstrate that RIXS can clarify the magnon-Stoner interactions in itinerant correlated flat band systems.