Bandwidth controlled half-metallicity in a ferromagnetic metal: ab initio calculations

We report the observation of the emergence of a half-metallic phase in a ferromagnetic metal, SrRuO<SUB>3</SUB>, via Ti substitution at the Ru sites employing state-of-the-art ab initio calculations. Ti<SUP>4+</SUP> (d<SUP>0</SUP> electronic configuration) substitution is manifested in the form of valence-band narrowing and enhancement of the local moment of the otherwise highly extended 4d electrons. The energy gap between t<SUB>2g</SUB> and e<SUB>g</SUB> bands gradually increases with the increase in x in SrRu<SUB>1-x</SUB>Ti<SUB>x</SUB>O<SUB>3</SUB> and becomes larger than 2 eV at x=0.875. Subsequently, a gap appears at the Fermi level, ε<SUB>F</SUB>, in the up-spin density of states, while the down-spin states contribute at ε<SUB>F</SUB> characterizing the system as a half-metallic ferromagnet. These results, thus, demonstrate a way to engineer metallicity in a ferromagnet leading to a half-metallic behavior