Degree Type

Thesis

Date of Award

1-1-2002

Degree Name

Master of Science

Department

Physics and Astronomy

Major

Condensed Matter Physics

Abstract

In order to determine the interactions responsible for magnetic ordering in RCo2Ge2 compounds, where R is a rare earth element, it is necessary to obtain an accurate measurement of the wave vector and orientation of the moments. Resonant and nonresonant x-ray scattering experiments were performed in order to determine the magnetic structure of single crystal compounds of GdCo2Ge2 and NdC02Ge2. Both compounds order antiferromagnetically with a wave vector along the c-direction. GdCo2Ge2 orders in an incommensurate state characterized by a propagation wave vector [Tau] = (0 0 [Tau subscript z]). The value of [Tau subscript z] is temperature dependent and approaches 0.932(±0.002) r.l.u. below T[Subscript N]= 32.9 K. A peak corresponding to 3[Tau subscript z] was also observed at T= 6K. By comparison with theoretical cross sections, a Q dependent measurement indicates that the moments are aligned perpendicular to the c-axis. Susceptibility measurements on NdCo2Ge2 indicate that two transitions may occur at low temperature. An incommensurate structure was found with a wave vector (0 0 [Tau subscript z]) and [Tau subscript z]= 0.7420(±0.0003) r.l.u. An extensive search was carried out for a second transition, but no second phase was detected.

DOI

https://doi.org/10.31274/rtd-20200723-3

Copyright Owner

William Stanley Good

Language

en

OCLC Number

51007838

File Format

application/pdf

File Size

54 pages

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