Charge to spin current efficiency studied by spin torque ferromagnetic resonance in various metal heterostructures
Abstract/Contents
- Abstract
- The Spin Hall effect (SHE) has been intensively studied because of its capability to generate pure spin currents and its potential application in manipulating magnetic moments. Several candidate materials have been reported to have a large spin Hall angle (SHA) through a variety of experiments. This dissertation summarizes my work on the SHE in several different heterostructures using spin torque ferromagnetic resonance (STFMR). In the first part of this work, I describe the construction of a high frequency probe system for STFMR measurement and use the technique to determine the SHA. We carefully study the interface in the SHE measurement. In most of the prior experiments, the ferromagnetic layer was attached to the candidates and used to detect the spin current intensity from the spin transfer torque. However, this introduces a new interface and causes barrier for spin diffusion. Careful study of the interface is discussed in this thesis and possible improvement of the interface is demonstrated. We use different ferromagnetic (FM) materials to measure the SHA of platinum in STFMR and prove the importance of the interface in this measurement. We derive the spin transparency of the interface from the spin diffusion model and find its relationship to spin mixing conductance, which can be extracted from FMR. In the second part of this work, Ir-Mn alloys, which are typical antiferromagnetic materials over certain compositions due to the special spin structure of Mn, are tested for SHE. Large SHA is observed in 1:1 and 1:3 for polycrystalline films and even larger SHA is observed in single crystalline IrMn3 grown on (001) MgO grown by magnetron sputtering. We observe a strong crystallographic orientation dependent SHE in IrMn3 and Ir20Mn80 films, but not in IrMn and Ir60Mn40 films.
Description
| Type of resource | text |
|---|---|
| Form | electronic; electronic resource; remote |
| Extent | 1 online resource. |
| Publication date | 2015 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Associated with | Zhang, Weifeng |
|---|---|
| Associated with | Stanford University, Department of Materials Science and Engineering. |
| Primary advisor | Brongersma, Mark L |
| Primary advisor | Parkin, Stuart S. P |
| Thesis advisor | Brongersma, Mark L |
| Thesis advisor | Parkin, Stuart S. P |
| Thesis advisor | Harris, J. S. (James Stewart), 1942- |
| Advisor | Harris, J. S. (James Stewart), 1942- |
Subjects
| Genre | Theses |
|---|
Bibliographic information
| Statement of responsibility | Weifeng Zhang. |
|---|---|
| Note | Submitted to the Department of Materials Science and Engineering. |
| Thesis | Thesis (Ph.D.)--Stanford University, 2015. |
| Location | electronic resource |
Access conditions
- Copyright
- © 2015 by Weifeng Zhang
- License
- This work is licensed under a Creative Commons Attribution 3.0 Unported license (CC BY).
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