The search for artificial structure with tunable topological properties is an
interesting research direction of today's topological physics. Here, we
introduce a scheme to realize `topological semimetal states' with a
three-dimensional periodic inductor-capacitor (LC) circuit lattice, where the
topological nodal-line state and Weyl state can be achieved by tuning the
parameters of inductors and capacitors. A tight-binding-like model is derived
to analyze the topological properties of the LC circuit lattice. The key
characters of the topological states, such as the drumhead-like surface bands
for nodal-line state and the Fermi-arc-like surface bands for Weyl state, are
found in these systems. We also show that the Weyl points are stable with the
fabrication errors of electric devices.Comment: 4 figure