  Structural, electronic and magnetic properties of bulk ilmenite CoTiO$_3$ are
analyzed in the framework of density functional theory (DFT), using the
generalized gradient approximation (GGA) and Hubbard-corrected approaches. We
find that the G-type antiferromagnetic (G-AFM) 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
intra-layer magnetic ordering. This would result in the individual planes
remaining ferromagnetic even at temperatures above the N\'{e}el 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 $\text{CoTiO}_3$,
which will determine its magnon properties, including topological aspects.
