Robust surface modes have been the hallmark of various topological phases. Usually, one needs a fully gapped spectrum (insulators) or a Fermi surface of reduced dimensionality (Weyl/nodal semimetals) to observe surface modes, especially for chiral ones. Whether metals with a normal Fermi surface can exhibit interesting surface modes has been a intriguing and hard question. Here, as initial explorations, we show that a Floquet driven system in 3D can give rise to a chiral hinge mode despite its 2D Fermi surfaces. This is related to the peculiar localization of eigenstates into quasi-1D regions, and the boundaries completely reconstruct all of its eigenstates forming 1D chiral hinge states in certain boundaries. Numerics demonstrate that such hinge modes exist in a wide region of parameter space. Such results could serve as stepping stones for a further explorations of possible topological theories of systems with a normal Fermi surfaces.
2009: Undergrad at Beijing Normal University
2016: PhD at Ohio State University
2016-2019: Postdoc, University of Pittsburgh
2019-2021: Guest Scientist, Max Planck Institute for the Physics of Complex Systems, Dresden
2021-Now: KITS, UCAS, Beijing
Research interest: Cold atom theories, especially for highly non-equilibrium phases of matter, i.e. time crystals, anomalous Floquet insulators, localization, and thermalization issues.