The electronic structure of a weakly correlated antiferromagnetic metal, SrCrO₃: First-principles calculations

On the basis of our idea of degree modulation, by using systematic first-principles calculations, we study the electronic structure and magnetic properties of SrCrO₃. Our results suggest that SrCrO₃ is a weakly correlated antiferromagnetic (AF) metal, a very rare situation in transition-metal oxides. Among various possible AF states, C-type spin ordering with a small amount of orbital polarization (the d_{x y} orbital is more occupied than the d_yz/zx orbital) is favored. The detailed understanding of the mechanism that stabilizes the C-type AF state is analyzed on the basis of the competition between itinerant Stoner instability and superexchange, and our results suggest that magnetic instability rather than lattice or charge instabilities plays an important role in this system. The experimentally observed c-axis compressed tetragonal distortion can be naturally explained with the C-type AF state. By using the LDA+U method to study this system, we show that the wrong ground state will be obtained if U is large.