4f Electron Localization–Delocalization studies in CeMg3 and PrMg3 alloys under Pressure

The pressure dependence of magnetic moment in CeMg${}_3$ and PrMg${}_3$ has been studied through ab initio electronic structure calculations based on density functional theory (DFT). Positive as well as negative pressure conditions were simulated by different degrees of unit cell compression or expansion and a fit of the total energy to the Birch–Murnaghan equation of state. At ambient and negative pressures, the calculated magnetic moments for both the compounds reveal localized behaviour of 4$f$ electrons. For increasing positive pressures, the magnetic moment of Ce in CeMg₃ has been observed to diminish smoothly, becoming zero at a critical pressure of P${}_C\sim$ 18 GPa indicative of pressure induced moment instability caused by an increase of $f$-conduction electron hybridization leading to delocalization of the 4$f$ electrons. In contrast, the magnetic moment of Pr in PrMg₃ does not show appreciable change with pressure, indicating strongly localized nature of the 4$f$ electrons.