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.Comment: 5 pages, 5 figures; ver.3: the sign convention for the Nernst
coefficient is change