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Spin dependent transport in ferromagnetic particles

Spintronics is an emerging technology that arises from the interplay between spin of the charge carrier and the magnetic property of the materials. The miniaturization of spintronic devices requires a deep understanding of ferromagnetic materials at the nanometer scale. This thesis studies the properties of ferromagnetic particles (2-5nm in diameter) using electron transport measurements. A technique to fabricate nanoparticle devices and incorporate microwave in the electron tunneling measurement of the particles is presented. Repeated microwave pulses can directly excite the magnetization of the particles without heating the electrons. Results of the transport measurements on Co particles will be discussed, which demonstrate that electron tunneling through a ferromagnetic particle can induce magnetization excitations in that particle. A physical model regarding the mesoscopic fluctuations is presented to address the current driven magnetization noise. Numerical simulations based on that model are performed to explain the experimental data and validate the model. Electron transport measurements on Ni, Fe, and Ni??Fe?? are conducted. The hysteretic behaviors of the particles in presence of electron tunneling have strong material dependence, which is mainly due to the magnetic shape anisotropy. Electron tunneling is a main source of magnetization noise, while other sources still need to be identified. Some data we collected from literature will be included in this thesis as an appendix.

Identiferoai:union.ndltd.org:GATECH/oai:smartech.gatech.edu:1853/52204
Date27 August 2014
CreatorsJiang, Wenchao
ContributorsDavidovic, Dragomir
PublisherGeorgia Institute of Technology
Source SetsGeorgia Tech Electronic Thesis and Dissertation Archive
Languageen_US
Detected LanguageEnglish
TypeDissertation
Formatapplication/pdf

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