Native Point Defects in Antiferromagnetic Phases of CrN

TL;DR

This study uses first-principles calculations to analyze native point defects in antiferromagnetic CrN, revealing nitrogen vacancies as the most likely defect and their impact on electronic and magnetic properties.

Contribution

It provides a detailed theoretical analysis of native point defects in AFM CrN, including formation energies, charge states, and experimental signatures, which was previously unexplored.

Findings

Nitrogen vacancies are the most probable native defects in AFM CrN.

Nitrogen vacancies exhibit two charge transition levels detectable by thermometry.

Defects induce partial spin polarization affecting transport properties.

Abstract

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.