Electronic correlations and topology in NpTe₂

UTe₂ has emerged as a promising and intensively studied candidate for spin-triplet superconductivity, where a paramagnetic normal state transitions into a superconducting phase driven by spin fluctuations. While the nature of the spin-triplet pairing and the associated topological properties in UTe₂ remain under active investigation, we present our findings on the related compound NpTe₂. Although structurally distinct from UTe₂, NpTe₂ exhibits intriguing electronic behavior. Density functional theory (DFT) calculations indicate that NpTe₂ is an enforced topological semimetal, characterized by a band degeneracy at the Fermi level. Notably, a semi-Dirac cone appears approximately 0.05 eV above the Fermi level, and a type-II Dirac nodal line is found in the 0.5–0.6 eV range. Magnetization, heat capacity, and electrical transport measurements on focused ion beam (FIB) micro-machined single crystals confirm a non-magnetic, semimetallic ground state. These measurements also reveal a small energy gap at the Fermi level, along with a characteristic resistivity plateau in the electrical resistivity at low temperatures.