Title: Flat Bands: catalogue, materials and Kagome metals

Speaker: Bogdan A. Bernevig (Princeton University)

Time: Oct. 18th (Wednesday), 20:00

Zoom ID: 860 6635 2058

Abstract: When electrons have quenched kinetic energy, interactions become crucial. If the bands are flat due to localization, the physics is boring. If however some of the bands are flat despite strong hopping, this betrays the fact that they are delocalized, and the projected interactions will be nontrivial. We present a method to create such flat bands based on geometrical insight, show that it can encompass all known flat bands, and that there is a large probability that such flat bands (which result from quantum interference) will be topological. Moreover, we find the first catalogue of such flat bands, show that most of the known famous Kagome metals are part of this catalogue. We further investigate a set of these Kagome compounds and show that their flat band are the result of more convoluted properties than simple Kagome flat bands. We present a Lego-like principle to explain the existence of flat bands in many Kagome metals, starting from a single building block, FeGe.

Bio:

Bogdan A. Bernevig is now a professor of physics at the Department of Physics, Princeton University. He graduated from Stanford University (bachelor's degree in physics and master's degree in mathematics in 2001) and received his PhD from Stanford University under Prof. Shoucheng Zhang. As a postdoctoral fellow he came to the Center for Theoretical Physics at Princeton University. Prof. Bernevig’s research interests include the application of topology in condensed matter physics, for example the fractional quantum hall effect and topological materials, high-temperature superconductivity, and novel physics in correlated electronic materials.  

Prof. Bernevig received the Sackler Prize in 2014 and the New Horizons in Physics Prize in 2016. In 2017 he was awarded a Guggenheim Fellowship and, in 2018, an Alexander von Humboldt Professorship. In 2019 he was awarded the James C. McGroddy Prize for New Materials from the American Physical Society. He was named a Fellow of the American Physical Society in 2022 for broad and significant contributions to the discovery and understanding of new topological quantum phases”. In 2023, Bernevig named EPS Europhysics Prize winner for research in condensed matter physics.