Dynamical Mean Field Theory and the Iron Pnictides and Chalcogenides*

Dynamical mean field theory (DMFT) in its combination with realistic electronic structure methods, now enables the computation of physical properties of materials starting from first principles. It also gives unexpected insights into the physics of strongly correlated systems.

We will illustrate these two aspects of the method, using the theory of Hund metals as an example. These are systems which derive their correlations from the Hund rule coupling rather than the Hubbard U. Primary examples are the iron pnictides and chalcogenides and the ruthenates.In this talk I will describe recent progress in understanding this class of materials using Dynamical Mean Field Theory and advanced quantum impurity solvers. We will stress in which way Hund correlations are different from those of materials near a Mott insulating state and on how the normal state characteristics of Hund metals impact their superconducting states at lower temperatures[2].

We will conclude with current directions to address outsanding challenges in this field[3].
[1] Deng et. al. arXiv:1708.05752
[2] Lee et. al. Phys. Rev. Lett. 121, 187003 (2018)
[3]P. Kent and G. Kotliar Science Vol 361, 6400, 348 Science (2018)