Nature of magnetic excitations in the iron pnictides and its pertinence to superconductivity as studied by inelastic neutron scattering

dc.contributor.advisor Robert J. McQueeney
dc.contributor.advisor Alan I. Goldman Tucker, Gregory
dc.contributor.department Physics and Astronomy 2018-08-11T19:11:35.000 2020-06-30T02:56:51Z 2020-06-30T02:56:51Z Thu Jan 01 00:00:00 UTC 2015 2001-01-01 2015-01-01
dc.description.abstract <p>Unconventional superconductivity and antiferromagnetism are often found in close proximity to one another. For the series of compounds Ba(Fe$_{1-x}$Co$_x$)$_2$As$_2$, which possesses both antiferromagnetism and superconductivity for the under-doped range of composition, this observation is certainly true. The close proximity, and in fact coexistence for under-doped Ba(Fe$_{1-x}$Co$_x$)$_2$As$_2$, of antiferromagnetism and superconductivity has encouraged speculation that antiferromagnetic spin fluctuations may mediate the electron pairing interaction in unconventional superconductors. Previous studies indicated that the spin fluctuations at optimally-doped Ba(Fe$_{1-x}$Co$_x$)$_2$As$_2$ are diffusive, while those at \bafeas are well defined spin wave excitations. Therefore, the nature of magnetic excitations in Ba(Fe$_{1-x}$Co$_x$)$_2$As$_2$ must change with the introduction of cobalt; but it is unclear if that change is merely a consequence of the loss of antiferromagnetic order, or a necessary ingredient for the appearance of superconductivity. To resolve this uncertainty, this work has been undertaken to study the spin fluctuations of five Ba(Fe$_{1-x}$Co$_x$)$_2$As$_2$ compositions varying in cobalt concentration from lightly-doped to nearly optimally-doped as well as representative samples of other, non-superconducting, transition metal substituted \bafeas compounds. The spin fluctuations of these samples, in their antiferromagnetically ordered and (where possible) superconducting states have been studied via triple-axis and time-of-flight inelastic neutron scattering, and definitively determine the importance of spin fluctuations for superconductivity in Ba(Fe$_{1-x}$Co$_x$)$_2$As$_2$.</p>
dc.format.mimetype application/pdf
dc.identifier archive/
dc.identifier.articleid 5462
dc.identifier.contextkey 7936140
dc.identifier.s3bucket isulib-bepress-aws-west
dc.identifier.submissionpath etd/14455
dc.language.iso en
dc.source.bitstream archive/|||Fri Jan 14 20:20:28 UTC 2022
dc.subject.disciplines Condensed Matter Physics
dc.subject.keywords Condensed Matter Physics
dc.subject.keywords iron pnictides
dc.subject.keywords neutron scattering
dc.subject.keywords superconductivity
dc.title Nature of magnetic excitations in the iron pnictides and its pertinence to superconductivity as studied by inelastic neutron scattering
dc.type article
dc.type.genre dissertation
dspace.entity.type Publication
relation.isOrgUnitOfPublication 4a05cd4d-8749-4cff-96b1-32eca381d930 dissertation Doctor of Philosophy
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