Full metadata record
| DC Field | Value | Language |
|---|---|---|
| dc.contributor.advisor | 이신범 | - |
| dc.contributor.author | Lee, Jaehyun | - |
| dc.date.accessioned | 2020-08-06T06:16:08Z | - |
| dc.date.available | 2020-08-06T06:16:08Z | - |
| dc.date.issued | 2020 | - |
| dc.identifier.uri | http://dgist.dcollection.net/common/orgView/200000335466 | en_US |
| dc.identifier.uri | http://hdl.handle.net/20.500.11750/12163 | - |
| dc.description | Hydrogenic control, reversible metal-insulator transition, room temperature ferromagnetism, La0.67Sr0.33MnO3, perovskite | - |
| dc.description.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. | - |
| dc.description.statementofresponsibility | N | - |
| dc.description.tableofcontents | 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 |
- |
| dc.format.extent | 40 | - |
| dc.language | eng | - |
| dc.publisher | DGIST | - |
| dc.title | Hydrogenic reversible control of both electric and magnetic properties in La0.67Sr0.33MnO3 perovskite | - |
| dc.type | Thesis | - |
| dc.identifier.doi | 10.22677/thesis.200000335466 | - |
| dc.description.alternativeAbstract | 스트론튬이 도핑된 란타늄 망간 산화물(La0.67Sr0.33MnO3)은 상온보다 높은 큐리온도(Curie temperature)를 가지며 거대 자기 저항(colossal magnetore-sistance)을 가지는 것으로 잘 알려진 강자성 산화물이다. 본 논문에서 우리는 수소가스 분위기에서의 열처리를 통해 수소 이온을 주입시켜 스트론튬이 도핑된 란타늄 망간 산화물 박막이 금속에서 비금속으로 전이되는 현상을 관측하고, 아르곤 분위기에서의 열처리를 통해 수소 이온을 다시 탈착시켜 본래의 금속 성질로 가역적으로 되돌아오는 것을 발견했다. 이러한 수소 이온 주입에 의해 형성된 새로운 비금속의 상태는 본래의 페로브스카이트 구조는 유지하면서, 강자성 특성이 보존됨을 확인하였다. X-선 광전자 분광법 측정을 통해 수소 이온의 주입에 의한 효과임을 뒷받침하는 결과를 실험적으로 확인하였고, 전자 투과 현미경 분석을 통해 수소 반응 이후에도 페로브스카이트 구조가 유지되는 것을 확인하였다. 이러한 수소 이온에 의한 가역적인 물성 조절이 가능함을 보여주는 우리의 연구는 새로운 지능형 반도체의 개발에 큰 흥미를 이끌 것이다. | - |
| dc.description.degree | Master | - |
| dc.contributor.department | Department of Emerging Materials Science | - |
| dc.contributor.coadvisor | Kim, June-Seo | - |
| dc.date.awarded | 2020/08 | - |
| dc.publisher.location | Daegu | - |
| dc.description.database | dCollection | - |
| dc.citation | XT.MD이73H 202008 | - |
| dc.date.accepted | 7/23/20 | - |
| dc.contributor.alternativeDepartment | 신물질과학전공 | - |
| dc.embargo.liftdate | 8/31/24 | - |
| dc.contributor.affiliatedAuthor | Lee, Jaehyun | - |
| dc.contributor.affiliatedAuthor | Lee, Shinbuhm | - |
| dc.contributor.affiliatedAuthor | Kim, June-Seo | - |
| dc.contributor.alternativeName | 이재현 | - |
| dc.contributor.alternativeName | Lee, Shinbuhm | - |
| dc.contributor.alternativeName | 김준서 | - |
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