Degree Type
Dissertation
Date of Award
2004
Degree Name
Doctor of Philosophy
Department
Physics and Astronomy
First Advisor
Ferdinando Borsa
Second Advisor
Marshall Luban
Abstract
In this thesis, our main interest has been to investigate the spin dynamics and quantum tunneling in single molecule magnets (SMMs). For this we have selected two different classes of SMMs: a ferromagnetic total high spin S = 10 cluster Fe8 and antiferromagnetic (AFM) ring-type clusters. For Fe8, our efforts have been devoted to the investigation of the quantum tunneling of magnetization in the very low temperature region. The most remarkable experimental finding in Fe8 is that the nuclear spin-lattice relaxation rate (1/T1) at low temperatures takes place via strong collision mechanism, and thus it allows to measure directly the tunneling rate vs. T and H for the first time. For AFM rings, we have shown that 1/T1 probes the thermal fluctuations of the magnetization in the intermediate temperature range. We find that the fluctuations are dominated by a single characteristic frequency which has a power-law T-dependence indicative of fluctuations due to electron-acoustic phonon interactions.
DOI
https://doi.org/10.31274/rtd-180813-165
Publisher
Digital Repository @ Iowa State University, http://lib.dr.iastate.edu
Copyright Owner
Seung-Ho Baek
Copyright Date
2004
Language
en
Proquest ID
AAI3158315
File Format
application/pdf
File Size
131 pages
Recommended Citation
Baek, Seung-Ho, "Spin dynamics and quantum tunneling in Fe8 nanomagnet and in AFM rings by NMR " (2004). Retrospective Theses and Dissertations. 1143.
https://lib.dr.iastate.edu/rtd/1143
Included in
Condensed Matter Physics Commons, Electromagnetics and Photonics Commons, Other Physics Commons
