Long-range interactions in the effective low-energy Hamiltonian of Sr2 IrO4: A core-to-core resonant inelastic x-ray scattering study

S. Agrestini, C. Y. Kuo, M. Moretti Sala, Z. Hu, D. Kasinathan, K. T. Ko, P. Glatzel, M. Rossi, J. D. Cafun, K. O. Kvashnina, A. Matsumoto, T. Takayama, H. Takagi, L. H. Tjeng, M. W. Haverkort

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Abstract

We have investigated the electronic structure of Sr2IrO4 using core-to-core resonant inelastic x-ray scattering. The experimental spectra can be well reproduced using ab initio density functional theory based multiplet ligand field theory calculations, thereby validating these calculations. We found that the low-energy, effective Ir t2g orbitals are practically degenerate in their crystal-field energy. We uncovered that Sr2IrO4 and iridates in general are negative charge transfer systems with large covalency and a substantial oxygen ligand hole character in the Ir t2g Wannier orbitals. This has far reaching consequences, as not only the on-site crystal-field energies are determined by the long-range crystal structure, but, more significantly, magnetic exchange interactions will have long-range distance dependent anisotropies in the spin direction. These findings set constraints and show pathways for the design of d5 materials that can host compasslike magnetic interactions.

Original languageEnglish
Article number205123
JournalPhysical Review B
Volume95
Issue number20
DOIs
StatePublished - 15 May 2017

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