High-Throughput Discovery of Chiral Carbon-Boron Semimetals with Weyl Topology and Phonon-Mediated Superconductivity

Chiral crystals provide a natural platform for unconventional topological fermions, while light-element carbon–boron frameworks are promising for phonon-mediated superconductivity owing to strong covalent bonding and high phonon frequencies. Here, we combine Wyckoff-position-based structure generation with high-throughput first-principles calculations to search for C–B crystals in selected hexagonal chiral space groups. Starting from 972 generated ${\mathrm{C}}_m{\mathrm{B}}_n$ structures ($m,n=1\text{–}4$), successive filters based on energetic stability, dynamical stability, electronic metallicity, topological band features, and thermal stability identify six stable candidates: $({\mathrm{C}}_3{\mathrm{B}}_2{)}_8$, $(\mathrm{C}{\mathrm{B}}_2{)}_3$, $(\mathrm{C}{\mathrm{B}}_4{)}_6$, $({\mathrm{C}}_3{\mathrm{B}}_2{)}_6$, $({\mathrm{C}}_2{\mathrm{B}}_3{)}_6$, and $(\mathrm{C}{\mathrm{B}}_2{)}_6$. These materials host diverse topological semimetal states near the Fermi level, including charge-one, charge-two, and charge-three Weyl points, nodal rings, and nodal-surface states. Notably, $({\mathrm{C}}_3{\mathrm{B}}_2{)}_8$ exhibits screw-symmetry-protected charge-three Weyl points and strong electron–phonon coupling, yielding a McMillan transition temperature of $31.1\mathrm{K}$ for the Coulomb pseudopotential parameter ${\mu }^{\ast }=0.10$. In addition, $(\mathrm{C}{\mathrm{B}}_2{)}_3$ hosts multiple charge-one Weyl points and pronounced anisotropic multiband superconductivity revealed by fully anisotropic Eliashberg calculations. These results extend the materials scope of topological semimetals with phonon-mediated superconductivity to chemically designed chiral light-element structures.