Intersecting topological nodal ring and nodal wall states in superhard superconductor FeB4

TL;DR

This paper predicts that the superhard superconductor FeB4 hosts intersecting topological nodal rings and wall states, combining topological properties with superconductivity and mechanical strength, suggesting potential for topological superconducting applications.

Contribution

It reveals the coexistence of topological nodal features and superconductivity in FeB4 through first-principles calculations, highlighting its potential as a topological superconductor.

Findings

FeB4 hosts intersecting nodal rings in specific planes.

Surface states confirm the topological nature of these features.

FeB4 combines superconductivity with topological and mechanical properties.

Abstract

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.