Electronic structure and magnetism in the frustrated antiferromagnet LiCrO₂: First-principles calculations

LiCrO₂ is a two-dimensional triangular antiferromagnet, isostructural with the common battery material LiCoO₂ and a well-known Jahn-Teller antiferromagnet NaNiO₂. As opposed to the latter, LiCrO₂ exibits antiferromagnetic exchange in the Cr planes, which has been ascribed to direct Cr-Cr d-d overlap. Using local density approximation (LDA) and LDA+U first-principles calculations, I confirm this conjecture and show that (a) direct d-d overlap is indeed enhanced compared to isostructural Ni and Co compounds, (b) the p-d charge-transfer gap is also enhanced, thus suppressing the ferromagnetic superexchange, (c) the calculated magnetic Hamiltonian maps well onto the nearest-neighbor Heisenberg exchange model, and (d) the interplanar inteaction is antiferromagnetic.