Magnetic ordering in Er₂Ti₂O₇ and elastic softening in Tb₂Ti₂O₇

Alqarni, Mona (2016) Magnetic ordering in Er₂Ti₂O₇ and elastic softening in Tb₂Ti₂O₇. Masters thesis, Memorial University of Newfoundland.

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Abstract

Geometric frustration occurs in the rare earth pyrochlores due to magnetic rare earth ions occupying the vertices of the network of corner-sharing tetrahedra. In this research, we have two parts. In the first one we study the phase transition to the magnetically ordered state at low temperature in the pyrochlore Er₂Ti₂O₇. The molecular field method was used to solve this problem. In the second part, we analyse the crystal electric field Hamiltonian for the rare earth sites. The rather large degeneracy of the angular momentum J of the rare earth ion is lifted by the crystal electric field due to the neighboring ions in the crystal. By rewriting the Stevens operators in the crystal electric field Hamiltonian ᴴCEF in terms of charge quadruple operators, we can identify unstable order parameters in ᴴCEF . These may be related to lattice instabilities in Tb₂Ti₂O₇.

Item Type: Thesis (Masters)
URI: http://research.library.mun.ca/id/eprint/11922
Item ID: 11922
Additional Information: Includes bibliographical references (pages 59-62).
Keywords: Magnetic Ordering, Elastic Softening, Tb₂Ti₂O₇, Er₂Ti₂O₇
Department(s): Science, Faculty of > Physics and Physical Oceanography
Date: May 2016
Date Type: Submission
Library of Congress Subject Heading: Solid state physics; Rare earths--Magnetic properties; Titanates--Properties; Titanates--Structure

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