High-order Fermi arcs and topological phase transitions in the kagome semimetal Pt3P2Te8

We design a kagome compound ${\mathrm{Pt}}_{3}{\mathrm{P}}_{2}{\mathrm{Te}}_{8}$ and find it is a topological semimetal with a symmetry-protected three-dimensional (3D) bulk Dirac point along the $\mathrm{\ensuremath{\Gamma}}$-A path. This Dirac point is not intrinsic to kagome lattice and brings a parity inversion, leading to topological surface states and fragile Fermi arcs on the (100) surface. These features are very close to the Fermi level and distinct from the bulk states, which suggests they can be observed in experiments. We further characterize the 3D bulk Dirac point and compute a high-order topological invariant, i.e., the change of the filling anomaly, whose value of 4 indicates the high-order bulk-hinge correspondence and the existence of high-order Fermi arcs. Moreover, ${\mathrm{Pt}}_{3}{\mathrm{P}}_{2}{\mathrm{Te}}_{8}$ exhibits rich topological phase transitions under hydrostatic pressure. Our results provide a potential platform to study topological properties related to 3D bulk Dirac points and pressure-induced topological phase transitions in the kagome lattice.