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Dissertation - AHJohnson - 5.pdf (14.3 MB)

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Growth and Characterization of Double Perovskite Buffer Materials for Thin Film Applications

Johnson, Alexanne Holcombe
http://rave.ohiolink.edu/etdc/view?acc_num=osu1397479975

Abstract Details

2014, Doctor of Philosophy, Ohio State University, Materials Science and Engineering.
Double perovskites of the A2BB’O6 form are of interest for their high Curie temperatures and interesting magnetic properties. Half-metallic double perovskites are of particular interest, but are difficult to produce as thin films. Pulsed laser deposition and ultrahigh vacuum sputtering require substrates with near perfect interfacial lattice matching to significantly reduce defect concentrations and promote ordering of the B/B’ site cations, which are known to control the magnetic and transport properties of these materials. A range of insulating double perovskite materials were investigated for use as buffer layer materials on which to grow half metallic, magnetoresistive Sr2FeMoO6 (SFMO). Chosen for their closely matching lattice parameters, insulting properties, and B/B’ cation ordering, Sr2AlXGa1-XTaO6, Sr2CrNbO6, and Sr2NiWO6 materials were synthesized and deposited by pulsed laser deposition. All buffer material thin films were characterized by XRD, AFM, and RBS. Critical film growth parameters were optimized to produce smooth, pure phase buffer films. SFMO was deposited on each buffer layer and its structure, surface morphology, and magnetic properties were analyzed. By comparing the SFMO magnetic moment of each sample, film quality was established and buffer layer properties were compared. STEM HAADF images were collected from select samples to verify the interface sharpness and possible defects contributing to the magnetic signal. Improved magnetic properties of buffer layer-SFMO films grown in the (001) orientation are shown to be the result of reduced interfacial strain due to minimal lattice mismatch between the buffer layer and SFMO. Growth quality could not be improved using buffer layers when SFMO was grown in the (111) orientation. Instead, our data suggests that SFMO has improved magnetic properties in this orientation because it is the preferred growth direction. Resulting magnetic and structural properties also suggest that low surface roughness was the dominant factor in reducing strain at the growth interface in the (111) orientated films.
Patricia Morris (Advisor)
Sheikh Akbar (Committee Member)
Michael Sumption (Committee Member)
Wolfgang Windl (Committee Member)
290 p.
Chemistry; Electromagnetics; Engineering; Solid State Physics
double perovskite; thin film deposition; x-ray diffraction characterization; surface morphology; magnetic characterization; buffer layer;

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Citations

  • Johnson, A. H. (2014). Growth and Characterization of Double Perovskite Buffer Materials for Thin Film Applications [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1397479975

    APA Style (7th edition)

  • Johnson, Alexanne. Growth and Characterization of Double Perovskite Buffer Materials for Thin Film Applications. 2014. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1397479975.

    MLA Style (8th edition)

  • Johnson, Alexanne. "Growth and Characterization of Double Perovskite Buffer Materials for Thin Film Applications." Doctoral dissertation, Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1397479975

    Chicago Manual of Style (17th edition)

osu1397479975
1,143
© 2014, some rights reserved.Creative Commons License Growth and Characterization of Double Perovskite Buffer Materials for Thin Film Applications by Alexanne Holcombe Johnson is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License. Based on a work at etd.ohiolink.edu.
This open access ETD is published by The Ohio State University and OhioLINK.