Antiferromagnetic transition in EuFe2As2:: A possible parent compound for superconductors

Ternary iron arsenide EuFe2As2 with ThCr2Si2-type structure has been studied by magnetic susceptibility, resistivity, thermopower, Hall, and specific-heat measurements. The compound undergoes two magnetic phase transitions at about 200 and 20 K, respectively. The former was found to be accompanied with a slight drop in magnetic susceptibility (after subtracting the Curie-Weiss paramagnetic contribution), a rapid decrease in resistivity, a large jump in thermopower, and a sharp peak in specific heat with decreasing temperature, all of which point to a spin-density-wave-like anti ferromagnetic transition. The latter was proposed to be associated with an A-type antiferromagnetic ordering of Eu2+ moments. Comparing with the physical properties of the isostructural compounds BaFe2As2 and SrFe2As2, we expect that superconductivity could be induced in EuFe2As2 through appropriate doping.