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• Magnetocrystalline anisotropy (MCA) increases when nitrogen is doped in the center of Pt layer. • MCA decreases when oxygen is doped in the center of Pt layer. • MCA decreases when nitrogen is doped in the center of Fe layer. • MCA decreases when oxygen is doped in the center of Fe layer. We studied the magnetic and electronic properties of L 1 0 -FePt alloy interstitial doped by oxygen or nitrogen using tetragonal distortion. We applied the density functional theory from first principle until the exchange–correlation energy; the generalized gradient approximation (GGA) of Perdew–Burke–Ernzerhof (PBE) was used. We found that the magnetocrystalline anisotropy MCA significantly increased for FePt:N Pt and our obtained value was 3.879 meV, which exceeds the pristine value. The anisotropy field H a , saturation magnetization M s and the energy product B H m a x were nearly close to the pristine value. These parameters can be tuned for practical applications. Calculations of formation energy E for reveal promotion of stability with doping. Density of state calculations showed strong hybridization of d -orbits with 2 p orbits of O or N. Moreover, with doping, there was an enhancement of energy states at Fermi level. [ABSTRACT FROM AUTHOR]

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]

Density Functional Theory and Monte Carlo Simulation were used to study the electronic and magnetic properties of X 3 Pt and XPt 3 binary alloys (where X = Fe, Co, or Ni), possessing L1 2 structure. Our results were carried out using a ferromagnetic phase for these binary alloys and showed a Curie temperature (T c) above room temperature for X 3 Pt and below room temperature for XPt 3. We calculated the exchange interactions J x x , J x P t , and J P t P t and found that J N i N i in the Ni 3 Pt compound was the strongest. Finally, we calculated the magnetocrystalline anisotropy for these alloys. • Electronic and magnetic properties of X3Pt and XPt3 binary alloys are studied using Density functional theory and Monte Carlo simulation. • Our results indicate that Curie temperature (T c) is above room temperature for X3Pt and below room temperature for XPt3 • The exchange interactions J x x , J x P t and J P t P t are studied and revealed that J N i N i in N i 3 P t is the strongest. • Weak hybridization between X-3d and Pt-5d orbitals near Fermi energy and strong hybridization between Pt-5d orbital and X-3d are observed. [ABSTRACT FROM AUTHOR]