NMR Studies of Multipolar Osmates*

The effects of doping on the electronic evolution of the Mott insulating state have been extensively studied in efforts to understand mechanisms of emergent quantum phases of materials. The study of these effects becomes ever more intriguing in the presence of entanglement between spin and orbital degrees of freedom. Here, we present a comprehensive investigation, employing nuclear magnetic resonance (NMR), muon spin spectroscopy (μSR), and magnetization measurement techniques, of charge doping in the double perovskite Ba2NaOsO6, a complex Mott insulator where such entanglement plays an important role. In this talk, I will describe  our findings  that include establishing that the insulating magnetic ground state evolves from canted antiferromagnet (cAFM) to Néel order for dopant levels exceeding ≈10%. Furthermore, we determine that a broken local point symmetry (BLPS) phase, precursor to the magnetically ordered state, occupies an extended portion of the (H−T) phase diagram with increased doping. This finding reveals that the breaking of the local cubic symmetry is driven by a multipolar order, most likely of the antiferro-quadrupolar type. Future measurements that could be  instrumental in determination of the precise nature of the identified multipolar order, will be discussed.