Low dimensional superconductivity in strontium titanate heterostructures
Abstract/Contents
- Abstract
- The two-dimensional confinement of electrons generates quantized subbands, primarily studied in semiconductor heterostructures, which play important roles determining their electrical properties. Despite the recent interest in the interplay between the subbands and superconductivity, their study has been limited due to the small range of materials candidates and the ability to control them at the atomic scale to form subbands. SrTiO3 is a perfect candidate for such study as it is intrinsically a wide-gap insulator, which becomes an n-type semiconductor by doping, allowing access to a clean well-defined system. In this work, single crystalline SrTiO3 heterostructures were fabricated using pulsed laser deposition, which had crystalline quality equal to bulk single crystals with their thickness controlled on the subnanometer scale. By fully exploiting the capability to form clean interfaces with other complex oxides, we engineered metal/SrTiO3 tunneling junctions which allowed us to address one of the longstanding questions regarding the origin of SrTiO3 superconductivity. From the tunneling spectroscopy of bulk and two-dimensional superconducting ground states in SrTiO3, two contrasting electron-phonon coupling strengths were obtained from the normal and the superconducting states, suggesting an unusual polaron formation in a weak coupling Bardeen-Cooper-Schrieffer superconductor. Furthermore, when two quantum wells are placed in parallel, the coupled quantum wells showed the coexistence of two distinct superconducting components originating from Cooper pairs on the different subbands, as evidenced by systematic variation in the upper critical fields. These results indicate the realization of an artificial multi-band superconductor enabled by two-dimensional confinement. These studies open a unique pathway to design and manipulate superconductivity in two-dimensions using oxide heterostructures.
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 | Inoue, Hisashi |
|---|---|
| Associated with | Stanford University, Department of Applied Physics. |
| Primary advisor | Hwang, Harold Yoonsung, 1970- |
| Thesis advisor | Hwang, Harold Yoonsung, 1970- |
| Thesis advisor | Beasley, Malcolm |
| Thesis advisor | Raghu, Srinivas, 1978- |
| Advisor | Beasley, Malcolm |
| Advisor | Raghu, Srinivas, 1978- |
Subjects
| Genre | Theses |
|---|
Bibliographic information
| Statement of responsibility | Hisashi Inoue. |
|---|---|
| Note | Submitted to the Department of Applied Physics. |
| Thesis | Thesis (Ph.D.)--Stanford University, 2016. |
| Location | electronic resource |
Access conditions
- Copyright
- © 2016 by Hisashi Inoue
- License
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
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