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Spin dynamics near a putative antiferromagnetic quantum critical point in Cu-substituted BaFe2As2 and its relation to high-temperature superconductivity

TitleSpin dynamics near a putative antiferromagnetic quantum critical point in Cu-substituted BaFe2As2 and its relation to high-temperature superconductivity
Publication TypeJournal Article
Year of Publication2015
AuthorsKim, MG, Wang, M, Tucker, GS, Valdivia, PN, Abernathy, DL, Chi, S, Christianson, AD, Aczel, AA, Hong, T, Heitmann, TW, Ran, S, Canfield, PC, Bourret-Courchesne, ED, Kreyssig, A, Lee, DH, Goldman, AI, McQueeney, RJ, Birgeneau, RJ
JournalPhysical Review B
Volume92
Pagination214404
Date Published12
Type of ArticleArticle
ISBN Number1098-0121
Accession NumberWOS:000365777800004
Keywordsfermi-liquid behavior, iron-based superconductors, kondo disorder, magnetic excitations, pairing mechanism, state, systems, transition, ucu5-xpdx
Abstract

We present the results of elastic and inelastic neutron scattering measurements on nonsuperconducting Ba(Fe0.957Cu0.043)(2)As-2, a composition close to a quantum critical point between antiferromagnetic (AFM) ordered and paramagnetic phases. By comparing these results with the spin fluctuations in the low-Cu composition as well as the parent compound BaFe2As2 and superconducting Ba(Fe1-xNix)(2)As-2 compounds, we demonstrate that paramagnon-like spin fluctuations are evident in the antiferromagnetically ordered state of Ba(Fe0.957Cu0.043)(2)As-2, which is distinct from the AFM-like spin fluctuations in the superconducting compounds. Our observations suggest that Cu substitution decouples the interaction between quasiparticles and the spin fluctuations. We also show that the spin-spin correlation length xi(T) increases rapidly as the temperature is lowered and find omega/T scaling behavior, the hallmark of quantum criticality, at an antiferromagnetic quantum critical point.

DOI10.1103/PhysRevB.92.214404
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