Absence of an appreciable iron isotope effect on the transition temperature of the optimally doped SmFeAsO(1-y) Superconductor

Parasharam M Shirage; Kiichi Miyazawa; Kunihiro Kihou; Hijiri Kito; Yoshiyuki Yoshida; Yasumoto Tanaka; Hiroshi Eisaki; Akira Iyo

doi:10.1103/PhysRevLett.105.037004

Absence of an appreciable iron isotope effect on the transition temperature of the optimally doped SmFeAsO(1-y) Superconductor

Phys Rev Lett. 2010 Jul 16;105(3):037004. doi: 10.1103/PhysRevLett.105.037004. Epub 2010 Jul 15.

Authors

Parasharam M Shirage¹, Kiichi Miyazawa, Kunihiro Kihou, Hijiri Kito, Yoshiyuki Yoshida, Yasumoto Tanaka, Hiroshi Eisaki, Akira Iyo

Affiliation

¹ National Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki 305-8568, Japan. [email protected]

PMID: 20867794
DOI: 10.1103/PhysRevLett.105.037004

Abstract

We report the iron (Fe) isotope effect on the transition temperature (T(c)) in oxygen-deficient SmFeAsO(1-y), a 50-K-class, Fe-based superconductor. For the optimally doped samples with T(c) = 54 K, a change of the average atomic mass of Fe (M(Fe)) causes a negligibly small shift in T(c), with the Fe isotope coefficient (α(Fe)) as small as -0.024 ± 0.015 (where α(Fe)=-d lnT(c)/dlnM(Fe)). 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-T(c) superconductors.