First-principles calculations to investigate magnetic, electronic, mechanical and dynamical properties of the bimetallic M-Pt (M: Mn Co and Ni) alloys

Abstract

This work reports on the magnetic, electronic, mechanical and dynamical characteristics of the bulk L10 ordered M-Pt (M = Mn, Co and Ni) bimetallic alloys. All calculations were carried out using the first-principles approach within the Density Functional Theory (DFT) method and the Generalized Gradient Approximation (GGA) functional. The CASTEP simulation code as embedded in the Materials Studio software was employed to perform all the calculations. The calculated equilibrium cell volumes are more than 95 % in agreement with the experimental data. Moreover, MnPt and NiPt alloys were confirmed to be stable at 0 K, while CoPt is metastable which is in good accordance with the experimental phase stability diagrams. The magnetic spins and electronic density of states showed that the MnPt alloy is highly magnetic over the CoPt and NiPt. The magnetic spin values for MnPt, CoPt and NiPt are 4.04 μB, 2.52 μB and 0.98 μB, respectively. MnPt and NiPt alloys were predicted to be mechanically and dynamically stable at ambient conditions since the elastic constants satisfied the Born stability conditions and there were no negative vibrations along high symmetry lines of the Brillouin zone in the phonon dispersion spectra. The CoPt alloy was found to be mechanically and dynamically stable from 13 GPa. More importantly, all M-Pt systems were predicted to be highly anisotropic, suggesting strong uniaxial magneto-crystalline anisotropy, making them very desirable in spintronic devices and magnetic recording devices.