Electronic Structure and Stability of Ni-Doped SiC Nanotubes: A DFT+U Study

Abstract Spin-polarized DFT+U calculations were carried out to systematically explore the influence of substitutional Ni incorporation on the structural, electronic, and magnetic characteristics of single-walled SiC nanotubes. The pristine nanotube exhibits a non-magnetic semiconducting ground state with a direct band gap of approximately 1.68 eV. Upon replacing a Si atom with Ni, the electronic structure undergoes substantial reconstruction, leading to a pronounced reduction of the band gap to 0.24–0.27 eV together with the appearance of spin-polarized impurity states in the vicinity of the Fermi level. Band-structure and spin-resolved density-of-states analyses demonstrate that strong hybridization between Ni-3d and neighboring Si/C-p orbitals is responsible for the observed electronic reconstruction, enhanced carrier transport, and magnetic ordering. The presence of spin-dependent states close to the Fermi energy indicates that the doped nanotube exhibits a conductive spin-polarized state with promising characteristics for spintronic applications. Structural relaxation, stress analysis, and atomic-force evaluation further confirm that the optimized Ni-substituted nanotube remains energetically favorable and mechanically stable after doping. These results demonstrate that substitutional Ni doping provides an effective route for tuning the band gap, inducing spin polarization, and improving the electronic functionality of quasi-one-dimensional SiC nanotubes, highlighting their potential for future nanoelectronic and spintronic technologies.