Synthesis of SmFeAsO by an easy and versatile route and its physical property characterization

We report synthesis, structure, electrical transport, and heat capacity of SmFeAsO. The title compound is synthesized by one-step encapsulation of stoichiometric FeAs, Sm, and Sm 2 O 3 in an evacuated ( 10 − 5 Torr ) quartz tube by prolong (72 h) annealing at 1100 ° C . The as-synthesized compound is crystallized in tetragonal structure with P 4 / n m m space group having lattice parameters a = 3.937 26 ( 33 ) A and c = 8.498 02 ( 07 ) A . The resistance ( R - T ) measurements on the compound exhibited ground state spin-density-wave (SDW)-like metallic steps below 140 K. Heat capacity C P ( T ) measurements on the title compound, showed an anomaly at around 140 K, which is reminiscent of the SDW ordering of the compound. At lower temperatures the C P ( T ) shows a clear peak at around 4.5 K. At lower temperature below 20 K, C p ( T ) is also measured under an applied field of 7 T. It is concluded that the C P ( T ) peak at 4.5 K is due to the antiferromagnetic ordering of Sm 3 + spins. These results are in confirmation with ordering of Sm in Sm 2 − x Ce x CuO 4 .