University of Missouri--Rolla
The magnetic and electronic structures of several rare earth-transition metal intermetallic compounds
Abstract
dc:description.abstract<p>"The crystallographic and magnetic properties of the LaNi<sub>5-x</sub>Fe<sub>x</sub> (1≤ x≤ 1.4) and LaNi<sub>5-x</sub>Mn<sub>5</sub> (x = 0, 1, 1.5, and 2) compounds have been studied by x-ray and neutron diffraction, SQUID and Mössbauer spectroscopy (LaNi<sub>5-x</sub>Fe<sub>x</sub> only). All of the samples crystallized in the hexagonal CaCu<sub>5</sub>-type structure with space group P6/mmm. Both Fe and Mn atoms preferentially occupy the 3g site in these compounds. The LaNi<sub>5-x</sub>Fe<sub>x</sub> samples exhibit ferromagnetic properties for x ≥ 1.2. The different magnetic behavior observed in LaNi<sub>4</sub>Fe suggests the coexistence of both short and long range magnetic ordering. The magnetic structure of LaNi<sub>5-x</sub>Mn<sub>5</sub> for x = 1.5 and 2 is described by a ferrimagnetic model. A ferromagnetic model gives the best fit of the neutron diffraction data for LaNi<sub>4</sub>Mn. Calculations of the nearest-neighbor environments suggest that the difference between the magnetic structures of LaNi<sub>5-x</sub>Mn<sub>5</sub> is due to the Mn dilution.</p> <p>The electronic structures of the LaNi<sub>5-x</sub>Fe<sub>x</sub> compounds with x = 1 and 2 have been modeled by the orthogonalized linear combination of atomic orbitals (OLCAO) method. Calculations of magnetic moments, total energy, which is related to the preference of Fe occupying the 3g site, and total density of states are consistent with the results from SQUID measurements, neutron diffraction data, and Mössbauer spectroscopy. The spin-polarized photoemission measurements did not provide quality data due to a sample magnetization problem caused by the low remanence of the samples. Spin-independent photoemission spectra for YCo<sub>5</sub>, NdCo<sub>5</sub>, and LaNi<sub>3.65</sub>Fe<sub>1.355</sub> are presented"--Abstract, page iv.</p>
Degree
thesis:*- Name thesis:degree_name
- Ph. D. in Physics
- Grantor
- University of Missouri--Rolla
- Year dc:date.available
- 2016
Author and committee
dc:creator, dc:contributor.*- Author dc:creator
-
- Tai, Chiu-Ying
Subjects
dc:subject × 1Identifiers
dc:identifier.*- Repository record dc:identifier
- https://scholarsmine.mst.edu/doctoral_dissertations/1368
- OAI identifier oai:identifier
- oai:scholarsmine.mst.edu:doctoral_dissertations-2370