Resonant x-ray studies in new generation honeycomb iridates

The Kitaev  Quantum spin liquid model can be realized in materials composed of d5 magnetic atoms in a strong octahedral crystal field and large spin-orbit coupling [1]. Of particular interest are Ir 4+ with a network of edge-sharing IrO6 octahedra arranged in a honeycomb lattice, for example, α-Li₂IrO₃ and NaIrO₃, in which strong Kitaev interactions are present. However, the existence of finite Heisenberg and pseudo-dipolar interactions in these compounds leads to long-range magnetic order at low temperatures [2,3]. Aiming to modify the magnetic interactions in these compounds, new honeycomb iridates, including Ag₃LiIr₂O₆ [4] and H₃LiIr₂O₆ [5], have been synthesized by introducing inter-honeycomb-layers Ag and H. However, to date, there is little empirical understanding of the influence of the intercalated atoms on the electronic structure, local Ir environment, and magnetism in this new generation of Kitaev honeycomb iridates. In this talk, I will present a series of resonant x-ray spectroscopy measurements on a set of honeycomb iridates, including Ag₃LiIr₂O₆ [6] and H₃LiIr₂O₆, and discuss the validity of the local j_eff = ½ picture in the context of the Kitaev model for these compounds.

[1] G.  Jackeli and G.  Khaliullin,  Phys.  Rev.  Lett.102,017205 (2009).

[2] S.C. Williams et al, Phys. Rev. B 93, 195158 (2106)

[3] S. H. Chun et al, Nat Phys,11, 462 (2015)

[4] F. Bahrami et al, Phys. Rev. B 103, 094427 (2021)

[5] K. Kitagawa et al., Nature 554, 341 (2018)

[6] A. de la Torre et al, Phys. Rev. B 104, L100416 (2021)