Evidence of structural phase transition in superconducting SmFeAsO_(1-x)F_x from 19^F NMR

TL;DR

This study presents evidence of a structural phase transition near 163 K in SmFeAsO_(0.86)F_(0.14), which also becomes superconducting at 48 K, based on resistivity, magnetization, and 19F NMR measurements.

Contribution

First detection of a structural phase transition in SmFeAsO_(1-x)F_x using 19F NMR, linking it to superconductivity in this compound.

Findings

Structural transition at 163 K identified by NMR.

Superconductivity observed at 48 K.

Potential link between structural transition and superconductivity.

Abstract

We report the resistivity, magnetization and 19^F NMR results in polycrystalline sample of SmFeAsO_(0.86)F_(0.14). The resistivity and the magnetization data show a sharp drop at 48 K indicating the superconducting transition. The nuclear spin-lattice rate (1/T_1) and spin-spin relaxation rate (1/T_2) clearly show the existence of a structural phase transition near 163 K in the sample which also undergo superconducting transition. This finding creates interest to explore whether this is unique for only Sm based systems or it is also present in other rare-earth based 1111 superconductors.