DFT Study of Hydrostatic Pressure Effects up to 1.0 GPa on the Electronic and Magnetic Properties of Laves Phases ErAl₂ and ErNi₂

This study employs DFT+U calculations to investigate the ferromagnetic properties of ErAl2 and ErNi2 Laves phases under an external hydrostatic pressure P (0 GPa ≤ P ≤ 1.0 GPa). The calculated magnetic moments per formula unit for both crystalline structures align with experimentally reported values: 4.40 μB/f.u. in the hard magnetization < 001> axis for ErAl2 and 5.56 μB/f.u. in the easy magnetization < 001> axis for ErNi2. The DFT results indicate that the magnetic moment remains unchanged up to 1 GPa of hydrostatic pressure, with no structural instabilities observed, as evidenced by a nearly constant formation energy for ErAl2 and ErNi2 alloys. The simulations confirm that the magnetic behavior of ErAl2 is primarily driven by the electrons localized in the f orbitals. In contrast, for ErNi2, both d and f orbitals significantly contribute to the total magnetic moment. Finally, the electronic specific heat coefficient was calculated and reported as a function of hydrostatic pressure up to P = 1.0 GPa for each Laves phase.