  Recently, a new class of second-order topological insulators (SOTIs)
characterized by an electronic dipole has been theoretically introduced and
proposed to host topological corner states. As a novel topological state, it
has been attracting great interest and experimentally realized in artificial
systems of various fields of physics based on multi-sublattice models, e.g.,
breathing kagome lattice. In order to realize such kind of SOTI in natural
materials, we proposed a symmetry-faithful multi-orbital model. Then, we reveal
several familiar transition metal dichalcogenide (TMD) monolayers as a material
family of two-dimensional SOTI with large bulk gaps. The topologically
protected corner state with fractional charge is pinned at Fermi level due to
the charge neutrality and filling anomaly. Additionally, we propose that the
zero-energy corner state preserves in the heterostructure composed of a
topological nontrivial flake embedded in a trivial material. The novel
second-order corner states in familiar TMD materials hold promise for revealing
unexpected quantum properties and applications.
