2026-09-21T06:09:17Zhttps://dspace.mit.edu/server/oai/requestoai:dspace.mit.edu:1721.1/324862022-01-13T07:54:21Zcom_1721.1_7582com_1721.1_7581col_1721.1_131022
Daniel G. Nocera.
Bartlett, Bart M
Massachusetts Institute of Technology. Dept. of Chemistry.
Massachusetts Institute of Technology. Department of Chemistry
2006-03-29T18:48:59Z
2006-03-29T18:48:59Z
2005
2005
http://hdl.handle.net/1721.1/32486
61857024
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 2005.
Vita.
Includes bibliographical references.
A series of pure iron jarosites (formula AFe₃(OH)₆(TO₄)₂) possessing the paradigmatic kagomé lattice has been prepared stoichiometrically pure through the use of a redox-based hydlrothermal synthetic strategy. This synthetic method allows us grow single crystals from which we fully characterize the structure and magnetic properties. Iron jarosites show signature spin frustrated behavior, indicated by a large Curie-Weiss constant, [theta] [approx.] -800 K, with a transition temperature, ... narrowly ranging from 56 - 65 K. Long-range antiferromagnetic order is due to a canted spin structure developed from the Dzyaloshinsky-Moriya (DM) interaction. Although the DM interaction energy is only 1.2 cm⁻¹, this is large enough to give rise to a 3-D magnetic structure, precluding the ability to study the ground state physics of a purely 2-D frustrated spin system. Copper hydroxy-bridged triangular species have been prepared and characterized both structurally and magnetically. Overall, the nearest-neighbor exchange interaction is found to be antiferromagnetic in each compound, with [Theta] ranging from -18 to -300 K, although the 1-D material lindgrenite, Cu₃(OH)₂)(MoO₄)₂, and the kagomé-lattice-containing material clinoatacamite, Cu₂(OH)₃Cl, show 3-D long-range ferromagnetic order. The compound zinc paratacamite presents the hallmark of an S = 1/2 Cu²⁺ compound possessing the kagomé lattice. This compound has magnetically isolated layers, and we find no evidence for magnetic ordering to temperatures down to 2 K, despite strong nearest-neighbor antiferromagnetic coupling, indicated by [Theta] [approx.] -300 K.
by Bart M. Bartlett.
Ph.D.
202 leaves
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9523313 bytes
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Massachusetts Institute of Technology
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http://dspace.mit.edu/handle/1721.1/7582
Chemistry.
Synthesis, structure, and magnetic properties of extended 2-D triangular lattices
Thesis
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<Abstract>A series of pure iron jarosites (formula AFe₃(OH)₆(TO₄)₂) possessing the paradigmatic kagomé lattice has been prepared stoichiometrically pure through the use of a redox-based hydlrothermal synthetic strategy. This synthetic method allows us grow single crystals from which we fully characterize the structure and magnetic properties. Iron jarosites show signature spin frustrated behavior, indicated by a large Curie-Weiss constant, [theta] [approx.] -800 K, with a transition temperature, ... narrowly ranging from 56 - 65 K. Long-range antiferromagnetic order is due to a canted spin structure developed from the Dzyaloshinsky-Moriya (DM) interaction. Although the DM interaction energy is only 1.2 cm⁻¹, this is large enough to give rise to a 3-D magnetic structure, precluding the ability to study the ground state physics of a purely 2-D frustrated spin system. Copper hydroxy-bridged triangular species have been prepared and characterized both structurally and magnetically. Overall, the nearest-neighbor exchange interaction is found to be antiferromagnetic in each compound, with [Theta] ranging from -18 to -300 K, although the 1-D material lindgrenite, Cu₃(OH)₂)(MoO₄)₂, and the kagomé-lattice-containing material clinoatacamite, Cu₂(OH)₃Cl, show 3-D long-range ferromagnetic order. The compound zinc paratacamite presents the hallmark of an S = 1/2 Cu²⁺ compound possessing the kagomé lattice. This compound has magnetically isolated layers, and we find no evidence for magnetic ordering to temperatures down to 2 K, despite strong nearest-neighbor antiferromagnetic coupling, indicated by [Theta] [approx.] -300 K.</Abstract>
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