Microscopic model of the mixed-valence iridates Ba₃MIr₂O₉ (M = In, Lu)

Mixed-valence iridates Ba₃MIr₂O₉ (M = In, Lu) where unpaired 5d electrons are localized on dimers of Ir atoms have been recently proposed as a source for novel spin liquid candidates[1]. Interestingly, the susceptibility measurements for Ba₃InIr₂O₉ show an anomalous temperature dependence with the Curie-Weiss law holding up to 80 K only. We performed ab-initio density functional based calculations combined with exact diagonalization of finite clusters and find that electronic states of these systems are driven by a temperature-dependent subtle interplay of spin-orbit coupling and Coulomb repulsion at the dimer level [2].

[1] T. Dey, M. Majumder, J. C. Orain, A. Senyshyn, M. Prinz-Zwick, F. Bert, P. Khuntia, N. Büttgen, A. A. Tsirlin, P. Gegenwart, arXiv:1702.08305 (2017)
[2] Ying Li, Alexander A. Tsirlin, Igor I. Mazin, Stephen M. Winter, and Roser Valentí, in preparation