Nanomechanical measurements of thin crystalline perovskite oxide membranes
Abstract/Contents
- Abstract
- Modern oxide materials have garnered significant interest toward them, as they are a class of materials that exhibit a variety of interesting physical properties, ranging from superconductivity to magnetism to ferroelectrics to multiferroics. Modern techniques in thin film fabrication of oxides have made it possible to make freestanding membranes of oxides and their heterostructures with precise control over thickness and composition. By lifting the thin films off from substrates and placing these membranes on a suitable substrate, the membranes can be manipulated mechanically in a desired manner. This serves as a powerful tool to measure the nanomechanical properties of thin oxide membranes by making freestanding structures and probing them using calibrated nanomechanical probes such as atomic force microscopy. Since freestanding structures are devoid of any substrate effects, it becomes straightforward to probe the membranes directly and measure the nanomechanical properties of oxides in the sub-100 nm thickness regime, which was not possible previously. In this work, I will discuss our efforts to measure and understand the nanomechanical properties of single crystalline oxide membranes. We transfer oxide membranes onto porous SiNx membrane to form freestanding circular drum-heads which are used to measure elastic and fracture properties of these oxides using atomic force microscopy. We find that the materials respond mechanically completely differently at the nanoscale compared to their bulk counterparts. We observe that nanoscale elasticity goes beyond the traditional linear and local description of elasticity and exhibits strain gradient elasticity, which stems from a strain gradient induced polarization known as flexoelectricity. Furthermore, we observe that the strain sustenance upon local loading is almost two orders of magnitude higher than the tensile limit for these materials in bulk, along with a fatigue lifetime of a billion cycles. These studies set the platform for studying and manipulating oxide membranes at the nanoscale, and also serve as the foundational experiments for nanomechanical studies of thin oxide membranes.
Description
| Type of resource | text |
|---|---|
| Form | electronic resource; remote; computer; online resource |
| Extent | 1 online resource. |
| Place | California |
| Place | [Stanford, California] |
| Publisher | [Stanford University] |
| Copyright date | 2021; ©2021 |
| Publication date | 2021; 2021 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Author | Harbola, Varun |
|---|---|
| Degree supervisor | Hwang, Harold Yoonsung, 1970- |
| Thesis advisor | Hwang, Harold Yoonsung, 1970- |
| Thesis advisor | Feldman, Ben (Benjamin Ezekiel) |
| Thesis advisor | Fisher, Ian R. (Ian Randal) |
| Degree committee member | Feldman, Ben (Benjamin Ezekiel) |
| Degree committee member | Fisher, Ian R. (Ian Randal) |
| Associated with | Stanford University, Department of Physics |
Subjects
| Genre | Theses |
|---|---|
| Genre | Text |
Bibliographic information
| Statement of responsibility | Varun Harbola. |
|---|---|
| Note | Submitted to the Department of Physics. |
| Thesis | Thesis Ph.D. Stanford University 2021. |
| Location | https://purl.stanford.edu/bv631jv7013 |
Access conditions
- Copyright
- © 2021 by Varun Harbola
- License
- This work is licensed under a Creative Commons Attribution 3.0 Unported license (CC BY).
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