New science nugget: Effects of doping in the s± gap. (Jan. 14)

The Optical Conductivity Group at LPEM, ESPCI

Our general main interest is to measure the optical conductivity in cristalline materials. The compounds at the center of our interest are multiferroic materials and of strongly correlated fermionic systems. Our research page shows these and more.

Multiferroic materials

The multiferroics totem
The Multiferroic Totem

Multiferroics are materials that show two simultaneous ferroic (electric, magnetic and elastic) orders. We are particularly interested in those materials that show the coexistence of electric and magnetic orders with a large interaction between them.

We aim to understand this magnetoelectric coupling from the lattice dynamics and electrically polar excitations. We concentrate on the phonon infrared response and look at its role in the formation of hybrid electromagnon excitations.

You can read more about our research on the subject and understand the picture to the left by going here.

Strongly Correlated Systems

Animated gif file showing the interaction of lattice ions with a Cooper pair
A Cooper Pair (with a really small correlation length)

Another topic of major interest for us is the optical conductivity of strongly correlated fermionic systems. These include cuprate and pnictide superconductors, manganites, heavy fermions, hydrides and whatnot.

The amazing properties observed in these systems come from the strong Coulomb repulsion sensed by electrons in these materials. Contrary to conventional metals, here Landau's Fermi liquid theory is no longer applycable.

The animation is a schematics representation of a Cooper pair interacting with phonons in conventional superconductors. You can click here to see why we think that this is not the picture in strongly correlated superconductors.