Native Point Defects in Antiferromagnetic Phases of CrN

We present a detailed analysis of the role of native point defects in the antiferromagnetic (AFM) phases of bulk chromium nitride (CrN). We perform first-principles calculations using local spin-density approximation, including local interaction effects (LSDA+U), to study the two lowest energy AFM models expected to describe the low-temperature phase of the material. We study the formation energies, lattice deformations and electronic and magnetic structure introduced by native point defects. We find that, as expected, nitrogen vacancies are the most likely defect present in the material at low temperatures. Nitrogen vacancies present different charged states in the cubic AFM model, exhibiting two transition energies, which could be measurable by thermometry experiments and could help identify the AFM structure in a sample. These vacancies also result in partial spin polarization of the induced impurity band, which would have interesting consequences in transport experiments. Other point defects have also signature electronic and magnetic structure that could be identified in scanning probe experiments.