First principles calculations of the electric field gradient tensors of Ba 2 NaOsO 6 , a Mott insulator with strong spin orbit coupling

• Published in: Journal of physics. Condensed matter 2020-09, Vol.32 (40), p.405802
• Main Authors: Cong, Rong, Nanguneri, Ravindra, Rubenstein, Brenda, Mitrović, V F
• Format: Article
• Language: English
• ISSN: 0953-8984; 1361-648X
• DOI: 10.1088/1361-648X/ab9056

We present first principles calculations of the electrostatic properties of Ba NaOsO (BNOO), a 5d Mott insulator with strong spin orbit coupling (SOC) in its low temperature quantum phases. In light of recent NMR experiments showing that BNOO develops a local octahedral distortion that is accompanied by the emergence of an electric field gradient (EFG) and precedes the formation of long range magnetic order (Lu 2017 14407, Liu 2018 224103; Liu 2018 863), we calculated BNOO's EFG tensor for several different model distortions. The local orthorhombic distortion that we identified as most strongly agreeing with experiment corresponds to a Q2 distortion mode of the Na-O octahedra, in agreement with conclusions given in (Liu 2018 224103). Furthermore, we found that the EFG is insensitive to the type of underlying magnetic order. By combining NMR results with first principles modeling, we have thus forged a more complete understanding of BNOO's structural and magnetic properties, which could not be achieved based upon experiment or theory alone.