Absence of an appreciable iron isotope effect on the transition temperature of the optimally doped SmFeAsO_{1-y} superconductor

TL;DR

This study investigates the iron isotope effect on the superconducting transition temperature in SmFeAsO_{1-y} and finds it to be negligible, contrasting with other Fe-based superconductors, implying different electron-phonon interactions.

Contribution

It provides the first measurement of the iron isotope effect in SmFeAsO_{1-y}, revealing a negligible impact on Tc and highlighting differences in electron-phonon coupling among Fe-based superconductors.

Findings

Negligible iron isotope effect on Tc in SmFeAsO_{1-y}

Contrasts with finite isotope effect in (Ba,K)Fe2As2

Suggests different electron-phonon interactions in these materials

Abstract

We report the iron (Fe) isotope effect on the transition temperature (Tc) in the oxygen-deficient SmFeAsO_{1-y}, a 50 K-class Fe-based superconductor. For the optimally-doped samples with Tc = 54 K, change of the Fe average atomic mass (MFe) causes a negligibly small shift in Tc, with the Fe isotope coefficient (alphaFe) as small as -0.024 \pm 0.015. This result contrasts with the finite, inverse isotope shift observed in optimally-doped (Ba,K)Fe2As2, indicating that the contribution of the electron-phonon interaction markedly differs between these two Fe-based high-Tc superconductors.