Neutron scattering study of underdoped Ba1-xKxFe2As2 (x=0.09 and 0.17) self-flux-grown single crystals and the universality of the tricritical point

TitleNeutron scattering study of underdoped Ba1-xKxFe2As2 (x=0.09 and 0.17) self-flux-grown single crystals and the universality of the tricritical point
Publication TypeJournal Article
Year of Publication2012
AuthorsRotundu CR, Tian W, Rule KC, Forrest TR, Zhao J, Zarestky JL, Birgeneau RJ
Journal TitlePhysical Review B
Volume85
Pages144506
Date Published04
Type of ArticleArticle
ISBN Number1098-0121
Accession NumberWOS:000302401400003
Keywordsantiferromagnetic order, phase, superconductivity
Abstract

We present a combination of elastic neutron scattering measurements in zero and 14.5 T and magnetization measurements in zero and 14 T on underdoped superconducting Ba1-xKxFe2As2 (x = 0.17), and the same measurements in zero field on a nonsuperconducting crystal with x = 0.09. The data suggest that the underdoped materials may not be electronic phase separated but rather have slightly inhomogeneous potassium doping. The temperature dependence of the magnetic order parameter below the transition of the sample with x = 0.09 is more gradual than that for the case of the undoped BaFe2As2, suggesting that this doping may be in the vicinity of a tricritical point. We advance therefore the hypothesis that the tricritical point is a common feature of all superconducting 122s. For the x = 0.17 sample, while T-c is suppressed from approximate to 17 to approximate to 8 K by a magnetic field of 14 T, the intensity of the magnetic Bragg peaks (1 0 3) at 1.2 K is enhanced by 10%, showing competition of superconductivity and antiferromagnetism. The intensity of the magnetic Bragg peaks (1 0 3) in the (T-c, T-N) temperature interval remain practically unchanged in 14.5 T within a 10% statistical error. The present results are discussed in the context of the existing literature.

URL<Go to ISI>://WOS:000302401400003
DOI10.1103/PhysRevB.85.144506
Alternate JournalPhys. Rev. B