Microstructural Analysis of Garnet-Heavy Metal Heterostructures
Rare earth iron garnets (REIGs) are a class of ferrimagnetic insulators desirable for their tunable magnetic properties. Saturation magnetization, perpendicular magnetic anisotropy (PMA), coercivity, and Gilbert damping are just a few characteristics that can be altered via elemental substitution or...
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| Format: | Thesis |
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Massachusetts Institute of Technology
2023
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| Online Access: | https://hdl.handle.net/1721.1/150294 |
| _version_ | 1826191672696897536 |
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| author | Gross, Miela Josephine |
| author2 | Ross, Caroline A. |
| author_facet | Ross, Caroline A. Gross, Miela Josephine |
| author_sort | Gross, Miela Josephine |
| collection | MIT |
| description | Rare earth iron garnets (REIGs) are a class of ferrimagnetic insulators desirable for their tunable magnetic properties. Saturation magnetization, perpendicular magnetic anisotropy (PMA), coercivity, and Gilbert damping are just a few characteristics that can be altered via elemental substitution or strain on the film [1,2]. These adjustable features make REIGs desirable magnetic materials for spintronics [3]. Spintronics devices aim to provide CMOS compatible microelectronics that utilize electric charge and magnetic moments to store and process information.
REIGs exhibit a variety of magnetic interactions, both bulk and interfacial, which are valuable for spintronics. Interfacial phenomena such as spin transfer torque, spin orbit torque, and interfacial Dzyaloshinskii-Moriya interaction have all been clearly observed in REIG-heavy metal heterostructures [4,5]. These specific events allow the magnetization of the REIG to be switched without the use of an external magnetic field at very low powers. Their fast switching is showcased in ultrafast domain wall velocities reported in Bi-substituted yttrium iron garnet and thullium iron garnet [6]. Plus, their high magnetooptical behavior allows REIGs to be studied via light techniques such as magnetooptical Kerr effect imaging and Brillouin light scattering [7].
While these magnetic interactions show promise for REIGs in spintronics applications, integrating these materials on Si requires further microstructure analysis. Polycrystalline dyprosium iron garnet (DyIG) has been successfully grown on Si with PMA due to an external rapid thermal anneal after pulsed laser deposition [8]. However, crystallization is limited to thicknesses above 20 nm. Furthermore, Pt is often used as a heavy metal for investigating interfacial phenomena in REIGs [9,10,11]. However, the REIG film growth is a kinetically active, high temperature, and oxygen rich environment. Pt durability during this process has yet to be studied. This thesis involves designing, building, and characterizing a heterostructure to achieve 10 nm thin DyIG and Y substituted DyIG on Si. A paramagnetic garnet, gadolinium gallium garnet, is used as a templating layer for the REIG, and a thin Pt diffusion barrier is sputtered between the two garnet layers. Microstructural and magnetic characteristics are investigated. |
| first_indexed | 2024-09-23T08:59:34Z |
| format | Thesis |
| id | mit-1721.1/150294 |
| institution | Massachusetts Institute of Technology |
| last_indexed | 2024-09-23T08:59:34Z |
| publishDate | 2023 |
| publisher | Massachusetts Institute of Technology |
| record_format | dspace |
| spelling | mit-1721.1/1502942023-04-01T03:58:11Z Microstructural Analysis of Garnet-Heavy Metal Heterostructures Gross, Miela Josephine Ross, Caroline A. Massachusetts Institute of Technology. Department of Electrical Engineering and Computer Science Rare earth iron garnets (REIGs) are a class of ferrimagnetic insulators desirable for their tunable magnetic properties. Saturation magnetization, perpendicular magnetic anisotropy (PMA), coercivity, and Gilbert damping are just a few characteristics that can be altered via elemental substitution or strain on the film [1,2]. These adjustable features make REIGs desirable magnetic materials for spintronics [3]. Spintronics devices aim to provide CMOS compatible microelectronics that utilize electric charge and magnetic moments to store and process information. REIGs exhibit a variety of magnetic interactions, both bulk and interfacial, which are valuable for spintronics. Interfacial phenomena such as spin transfer torque, spin orbit torque, and interfacial Dzyaloshinskii-Moriya interaction have all been clearly observed in REIG-heavy metal heterostructures [4,5]. These specific events allow the magnetization of the REIG to be switched without the use of an external magnetic field at very low powers. Their fast switching is showcased in ultrafast domain wall velocities reported in Bi-substituted yttrium iron garnet and thullium iron garnet [6]. Plus, their high magnetooptical behavior allows REIGs to be studied via light techniques such as magnetooptical Kerr effect imaging and Brillouin light scattering [7]. While these magnetic interactions show promise for REIGs in spintronics applications, integrating these materials on Si requires further microstructure analysis. Polycrystalline dyprosium iron garnet (DyIG) has been successfully grown on Si with PMA due to an external rapid thermal anneal after pulsed laser deposition [8]. However, crystallization is limited to thicknesses above 20 nm. Furthermore, Pt is often used as a heavy metal for investigating interfacial phenomena in REIGs [9,10,11]. However, the REIG film growth is a kinetically active, high temperature, and oxygen rich environment. Pt durability during this process has yet to be studied. This thesis involves designing, building, and characterizing a heterostructure to achieve 10 nm thin DyIG and Y substituted DyIG on Si. A paramagnetic garnet, gadolinium gallium garnet, is used as a templating layer for the REIG, and a thin Pt diffusion barrier is sputtered between the two garnet layers. Microstructural and magnetic characteristics are investigated. S.M. 2023-03-31T14:45:43Z 2023-03-31T14:45:43Z 2023-02 2023-02-28T14:36:04.397Z Thesis https://hdl.handle.net/1721.1/150294 0000-0002-2317-667X In Copyright - Educational Use Permitted Copyright MIT http://rightsstatements.org/page/InC-EDU/1.0/ application/pdf Massachusetts Institute of Technology |
| spellingShingle | Gross, Miela Josephine Microstructural Analysis of Garnet-Heavy Metal Heterostructures |
| title | Microstructural Analysis of Garnet-Heavy Metal Heterostructures |
| title_full | Microstructural Analysis of Garnet-Heavy Metal Heterostructures |
| title_fullStr | Microstructural Analysis of Garnet-Heavy Metal Heterostructures |
| title_full_unstemmed | Microstructural Analysis of Garnet-Heavy Metal Heterostructures |
| title_short | Microstructural Analysis of Garnet-Heavy Metal Heterostructures |
| title_sort | microstructural analysis of garnet heavy metal heterostructures |
| url | https://hdl.handle.net/1721.1/150294 |
| work_keys_str_mv | AT grossmielajosephine microstructuralanalysisofgarnetheavymetalheterostructures |