Out-of-plane magnetic anisotropy in bulk ilmenite CoTiO3

Structural, electronic, and magnetic properties of bulk ilmenite CoTiO3 are analyzed in the framework of density functional theory, using the generalized gradient approximation and Hubbard-corrected approaches. We find that the G-type antiferromagnetic structure, which consists of antiferromagnetically coupled ferromagnetic ab planes, is the ground state of the system, in agreement with experiments. Furthermore, cobalt titanates present two critical temperatures related to the breaking of the inter- and intralayer magnetic ordering. This would result in the individual planes remaining ferromagnetic even at temperatures above the Neel temperature. When spin-orbit coupling is included in our calculations, we find an out-of-plane magnetic anisotropy, which can be converted to an in-plane anisotropy with a small doping of electrons corresponding to about 2.5% Ti substitution for Co, consistent with experimental expectations. We thus present a disorder-dependent study of the magnetic anisotropy in bulk CoTiO3, which will determine its magnon properties, including topological aspects.