The effect of interstitial-site nitrogen on structural, elastic, and magnetic properties of face-center cubic Co

Cobalt plays a crucial role in the systematic understanding of magnetic phenomena originating from 3d transition metals. Particularly, recent studies of Co systems doped with nitrogen (Co-N) have attracted a lot of attention for applications in spintronics and high-density magnetic data-storage devices. In this work, in order to understand the effect of interstitial incorporation of N atoms into a face-center cubic (fcc) Co lattice, we have studied the structure, elastic, and magnetic properties of spherical-like bulk CoNx (x=0.06-0.07) samples. These samples were synthesized through a high-pressure solid-state metathesis reaction. We demonstrate that the use of a certain concentration of interstitial N atoms tends to stabilize the lattice of fcc Co at ambient conditions. Such a stabilizing effect is found to originate from the covalent bond between Co atoms and N atoms. High-pressure synchrotron x-ray diffraction indicates that the incorporation of N atoms into fcc Co has little effect on the elastic property up to 27.2GPa with a bulk modulus (B-0) of 200GPa; the latter is found to be comparable to that of fcc and hcp Co. CoNx samples exhibited ferromagnetic behavior with saturation magnetization up to 153.55emu/g and coercivity of 16.25Oe. The introduction of small amounts of nitrogen in the cobalt matrix was found to induce a significant decrease in the coercive force parameter.

Automated summary

The study investigates the effects of nitrogen atom incorporation into cobalt lattice on structure, elastic, and magnetic properties, revealing that a certain concentration of N atoms can stabilize the fcc Co lattice and induce ferromagnetic behavior. High-pressure x-ray diffraction shows little effect on elastic properties up to 27.2GPa, with CoNx samples exhibiting saturation magnetization up to 153.55emu/g and coercivity of 16.25Oe. Therefore, the introduction of a small amount of nitrogen can significantly reduce the coercive force parameter in the cobalt matrix.