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Title: Neutron scattering study of underdoped Ba 1-xK xFe₂As₂ (x=0.09 and 0.17) self-flux-grown single crystals and the universality of the tricritical point

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 Ba 1-xK xFe₂As₂ (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 122 s. For the x=0.17 sample, while T c is suppressed from ≈17 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 inmore » the context of the existing literature.« less
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Publication Date:
Publisher's Accepted Manuscript
Journal Name:
Physical Review. B, Condensed Matter and Materials Physics
Additional Journal Information:
Journal Volume: 85; Journal Issue: 14; Related Information: CHORUS Timestamp: 2017-04-06 08:59:01; Journal ID: ISSN 1098-0121
American Physical Society
Sponsoring Org:
Country of Publication:
United States
OSTI Identifier: