Condensed Matter Seminar - 2/12 - 12PM - Haim Beidenkopf "Topology and symmetry breaking in a Weyl-Kagome semimetal" - Jadwin Hall PCTS

Feb 12, 2024, 12:00 pm1:30 pm
Jadwin Hall - PCTS
Faculty, post docs, grads



Event Description

Many of the topological Weyl semimetals host also a Kagome crystal structure that together result in extremely rich electronic phenomenology. The bulk Weyl nodes and the diverging Berry curvature associated with them give rise to an intricate bulk-boundary correspondence hosting open-contour Fermi-arc modes on certain surfaces. The Kagome structure gives rise to a characteristic band structure that includes a flat band, and a Dirac node with a pair of saddle points, thus potentially promoting interaction effects due to high-density flat bands. We have investigated such a Weyl-Kagome semimetal and found evidence of both aspects. We visualize Fermi arc bands and also demonstrate their evolution from single-defect topological ring states. We further identify a new mechanism that flattens the saddle points induced by the Kagome structure into higher-order Van Hove singularities and tunes them to the Fermi energy. It results in a cascade of spontaneously symmetry-broken states that we visualize as well. Weyl-Kagome semimetals thus provide an exciting bedrock for a variety of exotic electronic states of matter.