Bulk topological Fermi arcs in heavy fermion systems*

We find that heavy fermion systems can have bulk ``Fermi arcs''. In an interacting electron system, we can define the effective Hamiltonian H_eff = H+Σ, where the many-body Hamiltonian is Hermitian, but the one-body quasiparticle Hamiltonian is non-Hermitian due to the finite quasiparticle lifetime. By introducing a topological theory of finite-lifetime quasiparticles, we can find that the low-energy dispersion of the Dirac material is reshaped and a topologically protected bulk Fermi arc appears[1,2]. Finite quasiparticle lifetime is a generic property of quantum many body systems, resulting from scatterings. The exceptional points of the non-Hermitian quasiparticle Hamiltonian matrix play a crucial role. With the use of the dynamical mean field theory (DMFT) calculation, we confirm our statement in Kondo insulators with a momentum-dependent hybridization in two-dimensions. We show that the concept of the exceptional points in the non-Hermitian quasiparticle Hamiltonian is one of powerful tools to predict new phenomena in strongly correlated electron systems.
[1]H. Shen, B. Zhen, and L. Fu, Phys. Rev. Lett. 120, 146402 (2018).
[2]V. Kozii and L. Fu, arXiv:1708.05841