Measurement of hall conductivity and gated magnetization by torque magnetometry
Abstract/Contents
- Abstract
- This thesis details the development of a new method to measure Hall conductivity for highly resistive samples utilizing a torque magnetometry method. Traditional methods to measure the Hall effect are inaccurate for highly resistive samples due to pollution from longitudinal resistance and sample heating. We have developed a new technique to measure the Hall effect using dissipationless currents and without point contacts to address such problems. A Corbino disk exhibits a magnetic dipole moment proportional to Hall conductivity when voltage is applied across a test material. This magnetic dipole moment can be measured through torque magnetometry. The symmetry of this contactless technique allows for the measurement of Hall conductivity in previously inaccessible materials. I first describe the method for fabricating cantilevers with integrated Corbino disks and the procedure used to measure Hall conductivity with such devices. The primary measurements of Hall conductivity through the new Corbino disk torque technique were performed on indium tin oxide (ITO). After performing tests for systematic errors with applied voltage and current, we measured the Hall conductivity of conductive ITO as a reference material to establish the accuracy of the Corbino disk torque technique. We next fabricated Corbino disks with resistive ITO and annealed across the metal-insulator transition to measure Hall conductivity of highly resistive samples. After annealing, we found magnetism in the ITO through both bulk torque magnetometry and the anomalous Hall effect. Such findings demonstrated both the accuracy of the new technique and the presence of debated inherent magnetism in annealed ITO. Having integrated a Corbino disk on a cantilever to measure the Hall effect, we are now expanding our ability to fabricate and measure cantilevers with integrated circuit elements. We have begun to measure torque magnetometry of miniaturized cantilevers with integrated gates. The initial miniaturized cantilevers were constructed to hold exfoliated graphene-hBN stacks. Smaller designs improved the torque sensitivity by a factor of 1000. Finally, such miniaturized cantilevers with metal layers could be extended in the future to measure Hall conductivity of smaller exfoliated flake samples.
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 | Mumford, Samuel Abraham |
|---|---|
| Degree supervisor | Kapitulnik, Aharon |
| Thesis advisor | Kapitulnik, Aharon |
| Thesis advisor | Hwang, Harold Yoonsung, 1970- |
| Thesis advisor | Kivelson, Steven |
| Degree committee member | Hwang, Harold Yoonsung, 1970- |
| Degree committee member | Kivelson, Steven |
| Associated with | Stanford University, Department of Physics |
Subjects
| Genre | Theses |
|---|---|
| Genre | Text |
Bibliographic information
| Statement of responsibility | Samuel Mumford. |
|---|---|
| Note | Submitted to the Department of Physics. |
| Thesis | Thesis Ph.D. Stanford University 2021. |
| Location | https://purl.stanford.edu/qq021gc7410 |
Access conditions
- Copyright
- © 2021 by Samuel Abraham Mumford
- License
- This work is licensed under a Creative Commons Attribution 3.0 Unported license (CC BY).
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