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TT: Fachverband Tiefe Temperaturen

TT 7: Correlated Electrons: Electronic Structure Calculations

TT 7.8: Vortrag

Montag, 18. März 2024, 11:30–11:45, H 3025

Dynamical mean-field theory study of the spin-orbit insulator Ba₂IrO₄: the role of spin-orbit coupling in the Mott transition — •Francesco Cassol¹, Léo Gaspard², Michele Casula¹, Cyril Martins², and Benjamin Lenz¹ — ¹IMPMC, Sorbonne University - CNRS, Paris, France — ²LCPQ, Université Paul Sabatier Toulouse III - CNRS, Toulouse, France

The discovery of the spin-orbit (SO) induced insulating ground state in Sr₂IrO₄ has triggered intense resarch efforts targeting materials with strong SO coupling. We focus here on Ba₂IrO₄, a sister compound of Sr₂IrO₄ with similar properties. In Ba₂IrO₄, the absence of structural distortions yields pseudo-spin states that are close in energy, casting doubts on the single band j_eff=1/2 picture invoked for Sr₂IrO₄. Its simple structure makes Ba₂IrO₄ also an ideal candidate to systematically study the interplay between SO coupling and Coulomb interactions in the metal-insulator transition. Based on an effective three-band model of Ba₂IrO₄, we investigate the evolution of the Mott transition within dynamical mean-field theory (DMFT). The corresponding phase diagram is studied with respect to the variation of the relevant couplings and temperature. We clarify the topological role of SO coupling and show that the paramagnetic insulating phase is recovered for realistic electron-electron interactions, thus establishing Ba₂IrO₄ as a SO-induced Mott insulator. Comparing our calculations with available angle-resolved photoemission spectra, we finally discuss the limitations of a single-site DMFT treatment and the role of antiferromagnetic fluctuations.

Keywords: iridates; dynamical mean-field theory; strong spin-orbit coupling; Mott insulator; spectral function