Harnessing the complexity of complex oxides
Abstract/Contents
- Abstract
- Human prosperity is driven by technology. And over the past 50 years, much of the tremendous progress in human prosperity has been driven by information technology, especially the semiconductor transistor and Moore's law. However, today Moore's law is ending. Going forward, humanity faces two broad possibilities: either stick with the transistor and settle for a reduced rate of technological progress or, as has been done many times in the past, develop a new computing paradigm with more initial difficulty but higher ultimate potential. One candidate materials platform for a future computing paradigm is complex oxides, whose complexity is both boon and bane. On the one hand, the complexity of complex oxides enables a wide range of tunable properties, such as ferromagnetism, ferroelectricity, and superconductivity. But on the other hand, their complexity makes them difficult to synthesize reliably and difficult to understand. In my PhD, I studied how the behavior of 3d electrons can be tuned in thin films of complex oxide materials. In my first major project, I studied how electrical conductivity could be turned on and off at the interface of LaAlO3/SrTiO3. And in my second major project, I studied how ferromagnetism could be turned on and off in RCo3, where R is a rare earth element. In my LaAlO3/SrTiO3 project, despite the interface's wide variation in reported electrical properties, I highlighted a scaling relationship between sheet carrier concentration and mobility common to nearly all research groups. I also discovered that the electrical transport is robust to the presence of magnetic and spin-orbit scatterers (Tm and Lu) at a 2% concentration in LaAlO3. In cobalt perovskites, I extended the phase diagram of thin film magnetism, exploring the roles of both chemical pressure (through A-site doping) and epitaxial strain. I discovered that although tensile epitaxial strain from SrTiO3 is enough to induce ferromagnetism in LaCoO3 and PrCoO3, it is not enough to induce ferromagnetism in P0.7Y0.3CoO3, which has a smaller and less cubic unit cell. X-ray magnetic circular dichroism revealed that although the Co ions Pr0.7Y0.3CoO3 in were not ferromagnetic, they still possessed magnetic moments, suggesting that the lack of ferromagnetism came from a lack of exchange rather than a lack of magnetic moment. These results highlight the importance of chemical bonding in stabilizing a ferromagnetic ground state and demonstrate new ways to tune magnetic order. Together, these projects provide new insights toward understanding and controlling the behavior of correlated 3d electrons. And they bring us a few steps closer to finally harnessing the complexity of the complex oxides.
Description
| Type of resource | text |
|---|---|
| Form | electronic; electronic resource; remote |
| Extent | 1 online resource. |
| Publication date | 2016 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Associated with | Sanders, Ted |
|---|---|
| Associated with | Stanford University, Department of Applied Physics. |
| Primary advisor | Suzuki, Yuri, (Applied physicist) |
| Thesis advisor | Suzuki, Yuri, (Applied physicist) |
| Thesis advisor | Hwang, Harold Yoonsung, 1970- |
| Thesis advisor | Qi, Xiaoliang |
| Advisor | Hwang, Harold Yoonsung, 1970- |
| Advisor | Qi, Xiaoliang |
Subjects
| Genre | Theses |
|---|
Bibliographic information
| Statement of responsibility | Ted Sanders. |
|---|---|
| Note | Submitted to the Department of Applied Physics. |
| Thesis | Thesis (Ph.D.)--Stanford University, 2016. |
| Location | electronic resource |
Access conditions
- Copyright
- © 2016 by Ted Sanders
- License
- This work is licensed under a Creative Commons Attribution Share Alike 3.0 Unported license (CC BY-SA).
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