uan Li received his B.S. degree from Peking University in 2004, and Ph.D. degree from Stanford University in 2010. He was a Humboldt Research Fellow at the Max Planck Institute for Solid State Research, Germany, from 2010 to 2012. Since 2012, he has been working as an associate professor at the International Center for Quantum Materials, Peking University, where he received tenure in 2018. His research involves the use of state-of-the-art scattering spectroscopic methods, in particular neutron and photon scattering, to study the structure and dynamics of materials with strong electron correlation and novel quasiparticle excitations. He was a recipient of Sir Martin Wood China Prize (2021).
Physicists are used to describing magnetism with models of interacting spins on lattices of magnetic ions. However, recent developments in topological quantum chemistry reveal the fact that a low-energy description of electrons are not necessarily “ionic”, but can instead feature other forms of tight-binding bases. In this talk, I will present an experimental reality of such a kind in the near-ferromagnetic binary compound of MnSi, by showing that the fundamental magnetic units are extended “molecular orbitals” consisting of three Mn atoms each. The key experimental evidence comes from inelastic neutron scattering measurements of the magnetic form factor, and it is further corroborated by first-principles calculation of the magnetic Wannier orbitals. The demonstrated interconnected magnetic molecular orbitals might change our way of looking at magnetism in quantum materials in which structural symmetry, electron itinerancy and correlations act in concert.