  Novel materials with both topological nontrivial states and superconductivity
have attracted considerable attention in recent years. Single-crystal FeB4 was
recently synthesized and demonstrated to exhibit superconductivity at
temperatures lower than 2.9 K, and its nanoindentation hardness was measured to
be 65 GPa. In this study, based on first-principles calculation and the
low-energy kp effective Hamiltonian, we found that this Pnnm-type superhard
FeB4 superconductor hosts topological behaviors with intersecting nodal rings
(INRs) in the k_x=0 and k_z=0 planes and nodal wall states in the k_y= {\pi}
and k_z= {\pi} planes. The observed surface drum-head-like (D-H-L) states on
the [100] and [001] surfaces confirmed the presence of INR states in this
system. According to our investigation results, FeB4, with its
superconductivity, superior mechanical behaviors, one-dimensional (1D) and
two-dimensional topological elements, and D-H-L surface states, is an existing
single-phase target material that can be used to realize the topological
superconducting state in the near future.
