We present a systematic study of the magnetic properties of $\mathrm{L}1{}_0$ binary alloys FeNi, CoNi, MnAl, and MnGa via two different density functional theory approaches. Our calculations show large magnetocrystalline anisotropies in the order $1{\mathrm{MJ}/\mathrm{m}}^3$ or higher for CoNi, MnAl, and MnGa, while FeNi shows a somewhat lower value in the range $0.48–0.77{\mathrm{MJ}/\mathrm{m}}^3$. Saturation magnetization values of $1.3\mathrm{MA}/\mathrm{m}$, $1.0\mathrm{MA}/\mathrm{m}$, $0.8\mathrm{MA}/\mathrm{m}$, and $0.9\mathrm{MA}/\mathrm{m}$ are obtained for FeNi, CoNi, MnAl, and MnGa, respectively. Curie temperatures are evaluated via Monte Carlo simulations and show $T_{\mathrm{C}}=916\mathrm{K}$ and $T_{\mathrm{C}}=1130\mathrm{K}$ for FeNi and CoNi, respectively. For Mn-based compounds Mn-rich off-stoichiometric compositions are found to be important for the stability of a ferro- or ferrimagnetic ground state with $T_{\mathrm{C}}$ greater than $600\mathrm{K}$. The effect of substitutional disorder is studied and found to decrease both magnetocrystalline anisotropies and Curie temperatures in FeNi and CoNi.

• Received 29 April 2014
• Revised 12 June 2014

DOI:https://doi.org/10.1103/PhysRevB.90.014402