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Hydrogenic reversible control of both electric and magnetic properties in La0.67Sr0.33MnO3 perovskite

Title
Hydrogenic reversible control of both electric and magnetic properties in La0.67Sr0.33MnO3 perovskite
Authors
Lee, Jaehyun
DGIST Authors
Lee, Jaehyun; Lee, ShinbuhmKim, June-Seo
Advisor(s)
이신범
Co-Advisor(s)
Kim, June-Seo
Issue Date
2020
Available Date
2020-08-06
Degree Date
2020/08
Type
Thesis
Description
Hydrogenic control, reversible metal-insulator transition, room temperature ferromagnetism, La0.67Sr0.33MnO3, perovskite
Abstract
Dynamic tuning of ion concentrations to create new functionalities in magnetoresistive La0.67Sr0.33MnO3 (LSMO) has attracted much attention. However, oxygen-vacancy-driven processes require extremely high temperatures (> 500oC) and take several days. Here, we found that by simply annealing platinum-dotted LSMO films in hydrogen and argon at the relatively low temperatures of 150–200oC for several minutes, we could achieve reversible changes in the resistivity over three orders of magnitude, with tailored ferromagnetic mag-netization. While oxygen-driven processes are usually accompanied by topotactic transitions between perovskite and brownmillerite, our reversible transition occurs in a perovskite. We suggest that this transition occurs due to electron-doping-induced modulation of double exchange interactions and/or lattice expansion, along with increases in the hydrogen concen-tration. Our findings offer high reproducibility, long-time stability, and linear multilevel ap-peal for ionotronic (ionic + electronic) applications.
Table Of Contents
Ⅰ. Introduction 1.1 Ionotronics: ionic control over materials’ functionalities 1 1.2 Lack of materials for ionic reversible control of both electrical and magnetic properties 1 Ⅱ. Experimental Methods 2.1 Deposition of La0.67Sr0.33MnO3 (LSMO) epitaxial films 4 2.2 Adsorption and desorption of hydrogen ions 4 2.3 Characterization of physical properties 5 2.4 Characterization of oxidation state 5 2.5 Characterization of structural properties 6 Ⅲ. Results and Discussion 3.1 Reversible metal-insulator transition by annealing ferromagnetic LSMO in hydrogen or argon at 200oC 7 3.2 Potential applications for ionotronic devices 12 3.3 Evidence of hydrogenic control 17 3.4 Hydrogen-driven electron doping 20 3.5 Hydrogen-driven reversible modulation of lattice volume in a perov-skite 21 3.6 Mechanism of hydrogen-driven metal-insulator transition in ferro-magnetic LSMO 24 3.7 Nanoscale observation of crystal structure in hydrogenated LSMO 25 Ⅳ. Conclusion
URI
http://dgist.dcollection.net/common/orgView/200000335466
http://hdl.handle.net/20.500.11750/12163
DOI
https://doi.org/10.22677/thesis.200000335466
Degree
Master
Department
Department of Emerging Materials Science
University
DGIST
Related Researcher
  • Author Lee, Shinbuhm Multifunctional films and nanostructures Lab
  • Research Interests Multifunctional films; Experimental condensed matter physics
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Collection:
Department of Emerging Materials ScienceThesesMaster


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