Effects of Hubbard U correction on the electronic and magnetic properties of Cr- and Ti-doped aluminum phosphide (AlP)

Chromium- and titanium-doped aluminum phosphides have the potential to exhibit half-metallic ferromagnetism, making them a promising candidates for spintronic applications. However, accurately capturing the electron–electron correlations within the d orbital to predict the magnetic and electronic properties remains a challenge when standard density functional theory (DFT) is used. In this study, we used the PBE functional and its Hubbard $U$ correction (PBE+U) to accurately capture the on-site Coulomb interaction of localized d orbitals. The results reveal that incorporating the Hubbard $U$ correction transforms the indirect bandgap of Al_0.75Cr_0.25P into the direct bandgap in the spin-down channel and improves the electronic character of Al_0.875Cr_0.125P from the metallic state to the half-metallic state. Moreover, it enhances the spin magnetic moment of both the dopant atoms and the doped systems and increases the occupancy of the d-orbital components in the spin-up channel. These findings offer strong evidence of the impressive half-metallic behavior of Cr- and Ti-doped AlP when the Hubbard $U$ correction is applied, highlighting their significant potential for future spintronic applications.