Constraints on the two-dimensional pseudospin-$\frac{1}{2}$Mott insulator description of $\mathrm{Sr_2IrO_4}

• Published in: Physical review. B 2022-06, Vol.105 (24)
• Main Authors: Zwartsenberg, B., Day, R. P., Razzoli, E., Michiardi, M., Na, M. X., Zhang, G., Denlinger, J. D., Vobornik, I., Bigi, C., Kim, B. J., Elfimov, I. S., Pavarini, E., Damascelli, A.
• Format: Article
• Language: English
• Subjects: angle resolved photoemission spectroscopy; CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; dynamical mean field theory; high temperature superconductors; Hubbard model; Mott insulators; spin-orbit coupling; spin-resolved photoemission spectroscopy
• ISSN: 2469-9950; 2469-9969

Sr2IrO4 has often been described via a simple, one-band pseudospin-$\frac{1}{2}$ model subject to electron-electron interactions on a square lattice, fostering analogies with cuprate superconductors believed to be well described by a similar model. In this work we argue - based on a detailed study of the low-energy electronic structure by circularly polarized spin and angle-resolved photoemission spectroscopy combined with dynamical mean-field theory calculations - that a pseudospin-$\frac{1}{2}$ model fails to capture the full complexity of the system. We show instead that a realistic multiband Hubbard Hamiltonian, accounting for the full correlated t2g manifold, provides a detailed description of the interplay between spin-orbital entanglement and electron-electron interactions and yields quantitative agreement with experiments. Our analysis establishes that the j3/2 states make up a substantial percentage of the low-energy spectral weight, i.e., approximately 74% as determined from the integration of the j-resolved spectral function in the 0 to -1.64eV energy range. Therefore, the results in our work are of relevance not only to Ir-based materials but also more generally to multiorbital materials with closely spaced energy scales.