Influence of oxygen and nitrogen doping on the structure and magnetic properties of CoNi alloy: First principle calculations.

We have studied the effects of oxygen and nitrogen doping as interstitial defects on the structure and magnetic properties of CoNi alloy using the first principle density functional theory, where we include the orbital-spin interaction in the calculations. Our calculations reveal that the CoNi:O Ni in the L1 0 -structure has a large enhancement in the saturation magnetization (M s) and a small reduction in the magnetic crystalline anisotropy (MCA). For CoNi:O Co , we found a small reduction in M s and MCA. However, for CoNi:N Co and CoNi:NNi there is always a reduction in M s and MCA. Therefore, the first alloy could be suitable for permanent magnets. A detailed analysis of other parameters, such as the magnetic hardness parameter (κ), optimum supercell parameters, anisotropy field (H a) , and formation energy (E f o r ) is presented. The interstitial oxygen doping enhances the magnetic properties. • The structural and magnetic properties of CoNi:D using the first principle are presented. • A large enhancement in the saturation magnetization has been predicted when adding oxygen. • The interstitial defect reduces the saturation magnetization and magnetocrystalline anisotropy energy. • These defective alloys are a potential candidate for permanent magnets. [ABSTRACT FROM AUTHOR]