Bogoliubov excitations in a Bose-Hubbard model on a hyperhoneycomb lattice

摘要

We study the topological properties of Bogoliubov excitation modes in a Bose-Hubbard model of three-dimensional (3D) hyperhoneycomb lattices.For the non-interacting case,there exist nodal loop excitations in the Bloch bands.As the on-site repulsive interaction increases,the system is first driven into the superfluid phase and then into the Mott-insulator phase.In both phases,the excitation bands exhibit robust nodal-loop structures and bosonic surface states.From a topology point of view,these nodal-loop excitation modes may be viewed as a permanent fingerprint left in the Bloch bands.