Doping dependence of the Nernst effect in Eu(Fe1-xCox)2As2 - departure   from Dirac fermions physics
  We report a systematic study of the transport properties in the series of Eu(Fe1-xCox)2As2 single crystals with x = 0, 0.15, 0.20 and 0.30. Spin-density-wave order is observed in the undoped and the least doped samples (x = 0, 0.15), while for x = 0.15 and 0.20 Eu(Fe1-xCox)2As2 becomes a superconductor. We found the properties of the parent EuFe2As2 compound well described by the Dirac fermions model, whereas cobalt doping caused an evolution of the system toward a regular metallic state. The antiferromagnetic ordering of the Eu2+ ions at T_N ~ 20 K has only minor influence on the measured quantities. 
Marcin Matusiak, Zbigniew Bukowski, and Janusz Karpinski
cond-mat.supr-con cond-mat.str-el