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

Language

en

Proquest ID

AAI3158315

File Format

application/pdf

File Size

131 pages

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