Physics & Astronomy Colloquium

3:30 PM, Wednesday, March 25, 2009
Room 155, Chem-Phys Building

Dr. Stephen Wilson
Lawrence Berkeley National Laboratory
The recent discovery of high temperature superconductivity (high-Tc) within the layered iron pnictides has generated a torrent of scientific investigation into the underlying mechanism driving the formation of their unconventional superconducting phase. These new iron pnictide-based systems now comprise a long sought comparison for resolving the physics fundamental to the phenomenon of high-Tc through comparison with the widely studied high-Tc copper oxides. One key element shared between their respective phase diagrams is the proximity of suppressed magnetic order to the onset of superconductivity. Magnetism is thought to play a vital role within the formation of superconducting condensate in both classes of high-Tc's, and investigations of the interplay between magnetism and superconductivity within these new iron pnictide superconductors are just beginning. In particular, the precise nature of the magnetic order within the undoped parent phase of these materials remains controversial. In this talk, I will present the results of our recent neutron scattering investigation of magnetic order in one such parent material, BaFe2As2 (Ba-122). Advances in crystal growth have allowed us to produce large, high quality, single crystals of Ba-122 that allow the intrinsic magnetic and structural phase behavior to be determined. Critical behavior near the onset of antiferromagnetic order in this system and its relation to the structural phase transition will be discussed.

Refreshments will be served in CP 177 at 3:15 PM