Layered Iron Pnicitdes and Chalchogenides: a new class of strongly correlated electron materials

The recently discovered iron  based superconductors

pose a new challenge to  many body theory methods.

We  will argue that these materials are Hunds

metals,  a new class of strongly correlated

materials where the correlations

are  controlled by the strength of the   Hunds rule  coupling

J rather than by the Hubbard U.   While correlations in these materials are

strong, their physical properties are strikingly different  from that of

transition metal oxides and the cuprates in particular.

We will describe  some   of the LDA+DMFT based

predictions for various spectroscopies: optical conductivity, photoemission

and inelastic neutron scattering.  We will compare the theoretical

predictions with experiments.

We will frame these questions in the more general context of our quest

for describing, understanding and predicting the physical

properties of strongly correlated materials.