Noncollinear magnetism and spin-orbit coupling in 5d pyrochlore oxide Cd2Os2O7

We investigated the electronic and magnetic properties of the pyrochlore oxide Cd${}_2$Os${}_2$O${}_7$ using the density-functional theory plus on-site repulsion ($U$) method, and depict the ground-state phase diagram with respect to $U$. We conclude that the all-in/all-out non-collinear magnetic order is stable in a wide range of $U$. We also show that the easy-axis anisotropy arising from the spin-orbit (SO) coupling plays a significant role in stabilizing the all-in/all-out magnetic order. A $\mathit{\text{pseudo}}\mathit{\text{gap}}$ was observed near the transition between the antiferromagnetic metallic and insulating phases. Finally, we discuss possible origins of the peculiar low-temperature($T$) properties observed in experiments.