Magnetic excitations in underdoped Ba(Fe1-xCox)(2)As-2 with x=0.047

TitleMagnetic excitations in underdoped Ba(Fe1-xCox)(2)As-2 with x=0.047
Publication TypeJournal Article
Year of Publication2012
AuthorsTucker GS, Fernandes RM, Li HF, Thampy V, Ni N, Abernathy DL, Bud'ko SL, Canfield PC, Vaknin D, Schmalian J, McQueeney RJ
Journal TitlePhysical Review B
Volume86
Pages024505
Date Published07
Type of ArticleArticle
ISBN Number1098-0121
Accession NumberWOS:000306189000002
Keywordsiron, scattering, superconductivity
Abstract

The magnetic excitations in the paramagnetic-tetragonal phase of underdoped Ba(Fe0.953Co0.047)(2)As-2, as measured by inelastic neutron scattering, can be well described by a phenomenological model with purely diffusive spin dynamics. At low energies, the spectrum around the magnetic ordering vector QAFM consists of a single peak with elliptical shape in momentum space. At high energies, this inelastic peak is split into two peaks across the direction perpendicular to QAFM. We use our fittings to argue that such a splitting is not due to incommensurability or propagating spin-wave excitations, but is rather a consequence of the anisotropies in the Landau damping and in the magnetic correlation length, both of which are allowed by the tetragonal symmetry of the system. We also measure the magnetic spectrum deep inside the magnetically ordered phase, and find that it is remarkably similar to the spectrum of the paramagnetic phase, revealing the strongly overdamped character of the magnetic excitations.

URL<Go to ISI>://WOS:000306189000002
DOI10.1103/PhysRevB.86.024505
Alternate JournalPhys. Rev. B