Electronic structure and magnetism in the frustrated antiferromagnet $\mathrm{Li}\mathrm{Cr}{\mathrm{O}}_{2}$: First-principles calculations

Electronic structure and magnetism in the frustrated antiferromagnet $Li Cr O_{2}$ : First-principles calculations

I. I. Mazin

Phys. Rev. B 75, 094407 – Published 6 March 2007

Abstract

$Li Cr O_{2}$ is a two-dimensional triangular antiferromagnet, isostructural with the common battery material $Li Co O_{2}$ and a well-known Jahn-Teller antiferromagnet $Na Ni O_{2}$ . As opposed to the latter, $Li Cr O_{2}$ 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.