Niels Bohr Institute > Calendar > 2009 > RPA approach to pairin...

RPA approach to pairing in multiorbital models of the Fe pnictides

Talk by Siegfried Graser 

The multiorbital character of the low-energy band structure and the existence of multiple disconnected Fermi surface sheets in the new iron based superconductors poses difficulties to a theoretical description of the superconducting ground state.

Using a multiorbital RPA description of the spin susceptibility we show that both, an extended s-wave state and a d-wave state, can be nearly degenerate in energy.
Details of the band structure, the doping and the relative strength of the different intra- and interorbital interactions can decide which ground state might be favored by a spin fluctuation mediated pairing interaction.