Effects of native defects on the structural and magnetic properties of hematite α-Fe2O3

Antiferromagnetic and ferromagnetic configurations of hematite alpha-Fe2O3 structures have been investigated by first-principles methods, which have been used to theoretically analyze the local structural and magnetic effects due to the presence of interstitial atoms such as hydrogen and oxygen. This study is based on the projector-augmented wave method within the local spin density approximation (LSDA) in addition to an on-site Coulomb correction of the Fe d orbitals (i.e., the LSDA + U-SIC method). The results demonstrate that this correction potential is important in achieving an accurate description of both the structural and the magnetic properties of alpha-Fe2O3. The ground state of alpha-Fe2O3 is the antiferromagnetic phase. The presence of oxygen vacancies, interstitial oxygen, and an interstitial hydrogen decreases the local Fe magnetic moment vertical bar M-s(Fe)vertical bar in both the ferro- and antiferromagnetic phases, although the hydrogen has a rather modest effect. The density of states calculations demonstrate that the presence of interstitial atoms and defects yields a small reduction in the material's electronic gap.