Orbital-quenching-induced magnetism in Ba_2NaOsO_6
arXiv:0709.2520 · doi:10.1209/0295-5075/80/37008
Abstract
The double perovskite \bnoo with heptavalent Os () is observed to remain in the ideal cubic structure ({\it i.e.} without orbital ordering) despite single occupation of the orbitals, even in the ferromagnetically ordered phase below 6.8 K. Analysis based on the {\it ab initio} dispersion expressed in terms of an Os -based Wannier function picture, spin-orbit coupling, Hund's coupling, and strong Coulomb repulsion shows that the magnetic OsO cluster is near a moment-less condition due to spin and orbital compensation. Quenching (hybridization) then drives the emergence of the small moment. This compensation, unprecedented in transition metals, arises in a unified picture that accounts for the observed Mott insulating behavior.
in press at Europhysics Letters