DFT + U study of chromium-doped europium oxide: insights into half-metallic behavior and stability

Abstract

The objective of this work is to apply density functional theory (DFT) with the inclusion of the Coulomb interaction (Hubbard U) to elements that possess d and f orbitals to explore the half-metallic properties of Europium oxide doped with Chromium. The formation energy recommends that these compounds (\({\text{Eu}}_{1-\text{x}}{\text{Cr}}_{\text{x}}\text{O}\)) are thermodynamically stable and our findings confirm that the introduction of Chromium (Cr) into the Europium Oxide (EuO) host matrix results in the emergence of a band gap in the minority spin channel, validating the half-metallic nature of our materials. Integer Bohr magneton values for total magnetizations confirm the half-metallic ferromagnetic behavior. The value of the half-metallic gap decreases when the concentration is increased. Remarkable results were observed on the EuO compound with the inclusion of Cr d content. The system undergoes a double-exchange mechanism which stabilizes ferromagnetic state. The estimated Curie temperature closely aligns with ambient conditions for concentrations of both 0.25 and 0.75, while reaching 169 K for a concentration of 0.5. These findings motivate further exploration into different concentrations and alternative dopant ions.

Graphical abstract