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Exploring the magnetic phases in dysprosium by neutron scattering techniques

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dc.contributorLeClair, Patrick R.
dc.contributorMewes, Claudia K. A.
dc.contributorHenderson, Conor
dc.contributorSuzuki, Takao
dc.contributor.advisorMankey, Gary J.
dc.contributor.authorYu, Jian
dc.contributor.otherUniversity of Alabama Tuscaloosa
dc.date.accessioned2017-03-01T17:21:41Z
dc.date.available2017-03-01T17:21:41Z
dc.date.issued2014
dc.descriptionElectronic Thesis or Dissertationen_US
dc.description.abstractWith one of the highest intrinsic magnetic moments (10.6 μ_B) among the heavy rare-earth elements, dysprosium (Dy) exhibits a rich magnetic phase diagram, including a few modulated magnetic phases. Aided by the Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction, the magnetic modulations propagate coherently over a long range, even with intervening non-magnetic layers. Neutron diffraction experiments were performed to determine the microscopic magnetic origin of the field induced phases in bulk Dy as a function of temperature, covering regions of the well-known ferromagnetic, helical antiferromagnetic, fan phases and several possible new phases suggested by previous studies. A short range ordered (SRO) fan phase was identified as the intermediate state between ferromagnetism and long range ordered (LRO) fan. The temperature range of a coexisting helix/fan phase was also determined. The magnetic phase diagram of Dy was thus refined to include the newly determined magnetic structures and the associated phase boundaries. Based on the period of the magnetic modulation and the average magnetization, the evolution of the spin arrangement upon heating was derived quantitatively for the modulated magnetic phases. To gauge the effect of nanostructuring on the magnetic phases with nonmagnetic Y layers, epitaxial Dy/Y superlattices of various layer thicknesses and repeats were fabricated by magnetron sputtering under carefully controlled conditions. X-ray characterizations confirmed that the crystallographic and interfacial qualities of the superlattices are comparable to those grown by MBE in previous studies. The macroscopic magnetization was characterized by magnetometry, whereas the microscopic magnetic structures were extracted from neutron diffraction and polarized neutron reflectometry (PNR) measurements. The ordering of helical modulation is sensitive to the interfacial roughness of the multilayer as well as the cooling histories. Off-specular PNR was applied the first time to characterize the helical domain structures in Dy/Y multilayers. The lateral correlation length in the helical magnetic structure was in the order of 100 nm.en_US
dc.format.extent127 p.
dc.format.mediumelectronic
dc.format.mimetypeapplication/pdf
dc.identifier.otheru0015_0000001_0001746
dc.identifier.otherYu_alatus_0004D_12136
dc.identifier.urihttps://ir.ua.edu/handle/123456789/2193
dc.languageEnglish
dc.language.isoen_US
dc.publisherUniversity of Alabama Libraries
dc.relation.hasversionborn digital
dc.relation.ispartofThe University of Alabama Electronic Theses and Dissertations
dc.relation.ispartofThe University of Alabama Libraries Digital Collections
dc.rightsAll rights reserved by the author unless otherwise indicated.en_US
dc.subjectCondensed matter physics
dc.subjectMaterials science
dc.titleExploring the magnetic phases in dysprosium by neutron scattering techniquesen_US
dc.typethesis
dc.typetext
etdms.degree.departmentUniversity of Alabama. Department of Physics and Astronomy
etdms.degree.disciplinePhysics
etdms.degree.grantorThe University of Alabama
etdms.degree.leveldoctoral
etdms.degree.namePh.D.

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