Degree Type

Dissertation

Date of Award

1999

Degree Name

Doctor of Philosophy

Department

Physics and Astronomy

First Advisor

Paul C. Canfield

Abstract

Anisotropic measurements of the magnetic and transport properties have been performed on high quality single crystals of the RAgSb2 series of compounds with R = Y, La-Nd, Sm, Gd-Tm. For all of these compounds except for ErAgSb2 and TmAgSb2, strong magnetic anisotropy created by CEF splitting of the Hund's rule ground state confines the moments to the basal plane. Additional anisotropy within the basal plane is also observed in DyAgSb2, leading to a series of metamagnetic transitions. Detailed analysis of the saturated moment and critical fields allows a determination of the net distribution of magnetic moments within each phase. The "4-position clock model" may be used to accurately model the observed metamagnetic phases. All of the compounds antiferromagnetically order at low temperatures except for the nonmagnetic compounds LaAgSb2 and YAgSb2 and CeAgSb2, which is ferromagnetic. The members of the series containing Y, La-Nd, and Sm show clear de Haas-van Alphen oscillations in fields as low as 30 kOe and at temperatures as high as 20 K. Analysis of the magnitude and angular dependence of these oscillations allows a determination of the shape of the Fermi surface. Throughout this series of compounds, the low temperature transverse magnetoresistance is large ( DrH /r0≈60 in SmAgSb2 at 55 kOe) and deviates strongly from quadratic behavior with field the dependence of DrH /r0 ranging between H0.8 to H1.5.

DOI

https://doi.org/10.31274/rtd-180813-13863

Publisher

Digital Repository @ Iowa State University, http://lib.dr.iastate.edu/

Copyright Owner

Kenneth Duane Myers

Language

en

Proquest ID

AAI9924750

File Format

application/pdf

File Size

171 pages

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