Synthesis of SmFeAsO by an Easy and Versatile Route and its Physical Property Characterization

TL;DR

This study presents a simple method to synthesize SmFeAsO, characterizes its structure and physical properties, and observes magnetic and electronic transitions related to SDW and AFM ordering.

Contribution

A new, straightforward synthesis route for SmFeAsO and detailed analysis of its structural, electrical, and magnetic properties.

Findings

Crystallizes in tetragonal P4/nmm structure

Exhibits SDW-like metallic behavior below 140 K

Shows AFM ordering of Sm3+ spins around 4.5 K

Abstract

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 Sm2O3 in an evacuated (10-5 Torr) quartz tube by prolong (72 hours) annealing at 1100oC. The as synthesized compound is crystallized in tetragonal structure with P4/nmm space group having lattice parameters a = 3.93726(33) A and c = 8.49802(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 CP(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 CP(T) shows a clear peak at around 4.5 K. At lower temperature below 20 K, Cp(T) is also measured under an applied field of 7 Tesla. It is concluded that the CP(T) peak at 4.5 K is due to the anti-ferromagnetic(AFM) ordering of Sm3+ spins. These results are in confirmation with ordering of Sm in Sm2-xCexCuO4.