Award Date

2009

Degree Type

Thesis

Degree Name

Master of Science in Physics

Department

Physics and Astronomy

Advisor 1

Andrew Cornelius, Committee Chair

First Committee Member

Micheal Pravica

Second Committee Member

Tao Pang

Graduate Faculty Representative

Adam Simon

Number of Pages

58

Abstract

Materials with a geometrically frustrated magnetic pyrochlore lattice have been of interest due to their unusual ground states. Tb 2 Ti 2 O 7 is known for having a spin liquid ground state which does not transition to a long-range ordered state down to at least 50 mK. Ho 2 Ti 2 O 7 has a macroscopically degenerate spin ice ground state which resembles that of the proton ordering in water ice. Heat Capacity measurements of Tb 2 Ti 2- x Sn x O 7 were done down to 0.36 K and AC magnetic susceptibility measurements of Ho 2- x Y x Ti 2 O 7 and Ho 2- x La x Ti 2 O 7 were done for frequencies from 10 Hz to 10 kHz down to 1.8 K, both in magnetic fields up to 9 T. These experiments were performed in an effort to further understanding of the factors that lead to their unusual behavior and to study the effects of introducing disorder through doping with nonmagnetic elements. Determination of the effect of an external field on the hyperfine crystal field at the Tb sites was done. In addition, unusual behavior in the ac susceptibility of the Ho samples at lower temperatures was observed.

Keywords

Atomic spins; Geometrical frustrations; Heat capacities; Holmiun titanates; Long range magnetic orders; Magnetic pyrochlore lattices; Pyrochlores; Terbium titanates

Disciplines

Condensed Matter Physics

Language

English


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