Electronic structure and magnetism in the frustrated antiferromagnet LiCrO2

TL;DR

This paper uses first principles calculations to analyze the electronic structure and magnetic interactions in LiCrO2, confirming the role of direct Cr-Cr d-d overlap in its antiferromagnetic properties.

Contribution

It demonstrates that enhanced direct d-d overlap and suppressed superexchange explain LiCrO2's antiferromagnetism, providing detailed electronic and magnetic insights.

Findings

Direct d-d overlap is enhanced in LiCrO2.

p-d charge transfer gap is increased, reducing ferromagnetic superexchange.

Magnetic interactions fit a nearest-neighbor Heisenberg model.

Abstract

LiCrO2 is a 2D 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 Cr planes, which has been ascribed to direct Cr-Cr d-d overlap. Using 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 Cr compounds, (b) p-d charge transfer gap is also enhanced, thus suppressing the ferromagnetic superexchange, (c) the calculated magnetic Hamiltonian maps well onto the nearest neighbors Heisenberg exchange model and (d) interplanar inteaction is antiferromagnetic.