Abstract

Strong electron–electron correlations can give rise to surprising co-operative phenomena; paradigmatic examples are high-temperature superconductivity, Mott insulating or heavy fermion behavior, orbital ordering. Explaining such many-body effects in materials is one of the grand challenges in condensed-matter physics, since they typically elude the simple static mean-field description. A major advance was the development of the dynamical mean-field theory (DMFT) and its combination with ab-initio techniques based on density-functional theory (DFT), leading to the DFT +DMFT method and its extensions [1,2].

In this talk I will shortly review the DFT +DMFT approach and its success. I will then present results for a paradigmatic group of systems, Sr2RuO4 and its family (Sr2XO4), unravelling the puzzling interplay of crystal-field effects, van-hove singularities, spin orbit interaction and Coulomb repulsion in these materials [3,4].

All calculations presented are based on our massively-parallel implementation of the DFT +DMFT method and use Quantum Monte Carlo (QMC) to solve the DMFT impurity problem [1,2].

[1] E. Pavarini, Solving the strong-correlation problem in materials, Rivista del Nuovo Cimento, Springer-Nature (2021)

[2] Dynamical Mean-Field Theory for Materials, in Eva Pavarini and Erik Koch (eds.), Simulating Correlations on Computers, Modeling and Simulation, Vol. 11, Verlag des Forschungszentrum Jülich, 2021, ISBN 978 -3-95806-529-1 https://www.cond-mat.de/events/correl21/manuscripts/pavarini.pdf

[3] N. Samani, G. Zhang and E. Pavarini, Phys. Rev. Lett. 132, 236505 (2024)

[4] G. Zhang and E. Pavarini, Phys. Rev. Lett. 131, 036504 (2023)