Phase diagram of superconductivity and antiferromagnetism in single crystals of Sr(Fe1-xCox)(2)As-2 and Sr1-yEuy(Fe0.88Co0.12)(2)As-2

TitlePhase diagram of superconductivity and antiferromagnetism in single crystals of Sr(Fe1-xCox)(2)As-2 and Sr1-yEuy(Fe0.88Co0.12)(2)As-2
Publication TypeJournal Article
Year of Publication2011
AuthorsHu RW, Bud'ko SL, Straszheim WE, Canfield PC
Journal TitlePhysical Review B
Volume83
Pages094520
Date Published03
Type of ArticleArticle
ISBN Number1098-0121
Accession NumberISI:000288385900009
Keywordscoexistence, magnetism
Abstract

We report magnetic susceptibility, resistivity, and heat capacity measurements on single crystals of the Sr(Fe1-xCox)(2)As-2 and Sr1-yEuy(Fe0.88Co0.12)(2)As-2 series. The optimal Co concentration for superconductivity in Sr(Fe1-xCox)(2)As-2 is determined to be x similar to 0.12. On the basis of this, we grew members of the Sr1-yEuy(Fe0.88Co0.12)(2)As-2 series so as to examine the effects of well-defined, local magnetic moments on the superconducting state. We show that superconductivity is gradually suppressed by paramagnetic Eu2+ doping and coexists with antiferromagnetic ordering of Eu2+ as long as T-c > T-N. For y >= 0.65, T-N crosses T-c and the superconducting ground state (as manifested by zero resistivity) abruptly disappears with evidence for competition between superconductivity and local moment antiferromagnetism for y up to 0.72. It is speculated that the suppression of the antiferromagnetic fluctuations of the Fe sublattice by coupling to the long-range order of the Eu2+ sublattice destroys bulk superconductivity when T-N > T-c.

URL<Go to ISI>://000288385900009http://prb.aps.org/pdf/PRB/v83/i9/e094520
DOI10.1103/PhysRevB.83.094520
Alternate JournalPhys. Rev. B