First-principles electronic structure of spinel LiCr2O4:: A possible half-metal -: art. no. 075117

We have employed first-principles electronic structure calculations to examine the hypothetical (but plausible) oxide spinel, LiCr2O4 with the d(2.5) electronic configuration. The cell (cubic) and internal (oxygen position) structural parameters have been obtained for this compound through structural relaxation in the first-principles framework. Within the one-electron band picture, we find that LiCr2O4 is magnetic, and a candidate half-metal. The electronic structure is substantially different from the closely related and well-known rutile half-metal CrO2. In particular, we find a smaller conduction-band width in the spinel compound, perhaps as a result of the distinct topology of the spinel crystal structure, and the reduced oxidation state. The magnetism and half-metallicity of LiCr2O4 has been mapped in the parameter space of its cubic crystal structure. Comparisons with superconducting LiTi2O4 (d(0.5)), heavy-fermion LiV2O4 (d(1.5)), and charge-ordering LiMn2O4 (d(3.5)) suggest the effectiveness of a nearly rigid band picture involving simple shifts of the position of E-F in these very different materials. Comparisons are also made with the electronic structure of ZnV2O4 (d(2)), a correlated insulator that undergoes a structural and antiferromagnetic phase transition.