4f Electron Localization–Delocalization studies in RAl2 (R = Ce, Eu and Gd) alloys under pressure

Abstract

First principles electronic structure and the pressure dependence of their magnetic moment have been calculated for RAl${}_2$ (R = Ce, Eu and Gd) alloys based on density functional theory (DFT). The variation in pressure conditions are simulated by various degree of unit cell compression. At ambient pressure, EuAl${}_2$ and GdAl${}_2$ reveal localized behaviour of 4$f$ electrons. Within the pressure range studied here, the $f$ band broadens a bit with pressure; the magnetic moment values remain almost unchanged suggesting much higher pressure may be required for visible delocalization. CeAl${}_2$ shows itinerant magnetism at ambient pressure; the magnetic moment of Ce in CeAl${}_2$ has been observed to diminish smoothly, becoming zero at a critical pressure of P${}_C$ $\sim$ 7.71 GPa indicative of pressure induced moment instability caused by an increase of $f$-conduction electron delocalization caused by increase of hybridization between 4$f$ electrons with conduction electrons.