Quantum oscillations in the parent magnetic phase of an iron arsenide   high temperature superconductor
  We report quantum oscillation measurements in SrFe2As2 - which is an antiferromagnetic parent of the iron-arsenide family of superconductors - known to become superconducting under doping and the application of pressure. The magnetic field and temperature dependences of the oscillations between 20 and 55 T in the liquid helium temperature range suggest that the electronic excitations are those of a Fermi liquid. We show that the observed Fermi surface comprising small pockets is consistent with the formation of a spin-density wave. Our measurements thus demonstrate that high Tc superconductivity can occur on doping or pressurizing a conventional metallic spin-density wave state. 
Suchitra E. Sebastian, J. Gillett, N. Harrison, P. H. C. Lau, C. H.   Mielke, G. G. Lonzarich