Iron isotope effect on the superconducting transition temperature and the crystal structure of FeSe_1-x

TL;DR

This study investigates how substituting iron isotopes in FeSe_1-x affects its superconducting transition temperature and crystal structure, revealing a notable isotope effect and associated structural changes.

Contribution

It provides the first detailed measurement of the iron isotope effect on T_c and crystal structure in FeSe_1-x, highlighting isotope-induced structural modifications.

Findings

Fe isotope substitution shifts T_c by 0.22K

Fe isotope effect exponent is approximately 0.81

Small structural changes accompany isotope substitution

Abstract

The Fe isotope effect (Fe-IE) on the transition temperature T_c and the crystal structure was studied in the Fe chalcogenide superconductor FeSe_1-x by means of magnetization and neutron powder diffraction (NPD). The substitution of natural Fe (containing \simeq 92% of ^{56}Fe) by its lighter ^{54}Fe isotope leads to a shift of T_c of 0.22(5)K corresponding to an Fe-IE exponent of \alpha_Fe=0.81(15). Simultaneously, a small structural change with isotope substitution is observed by NDP which may contribute to the total Fe isotope shift of T_c.