Growth and Characterization of Polycrystalline Rare-earth Iron Garnet Films and Heterostructures

Growth and Characterization of Polycrystalline Rare-earth Iron Garnet Films and Heterostructures
Author: Jackson J. Bauer
Publisher:
Total Pages: 198
Release: 2021
Genre:
ISBN:

Spintronics is a fast-developing field which makes use of the two spin states of the electron, and has the potential for more efficient, robust, and faster microelectronic devices. Thin films of rare-earth iron garnets, a class of insulating ferrimagnetic oxides, are particularly well suited to this application as the anisotropy, magnetization, magnetostriction, and damping can be easily controlled through selection of rare-earth ion and substrate. Previous work on garnets has focused on epitaxial single-crystal films grown on garnet substrates, which are expensive and not of commercial importance. Thus, it is of interest to grow nanometer scale thin films of garnets as polycrystalline layers on non-garnet substrates with perpendicular magnetic anisotropy. In this thesis, the growth of polycrystalline thin films of rare-earth iron garnets with controllable anisotropy and spin transport properties comparable to single crystal films is reported. Perpendicular magnetic anisotropy, which is essential for efficient manipulation of the magnetization through spin-orbit torque injection from an adjacent conductive layer, is achieved via control of the magnetoelastic anisotropy from thermal expansion mismatch between the film and substrate for europium iron garnet/quartz and dysprosium iron garnet/silicon. Heterostructures with a platinum overlayer allow investigation of the spin Hall magnetoresistance, which indicates a high degree of spin transparency at the interface. Next, a novel heterostructure is developed that allows for the growth of ultra-thin (

Microstructural Analysis of Garnet-heavy Metal Geterostructures

Microstructural Analysis of Garnet-heavy Metal Geterostructures
Author: Miela Josephine Gross
Publisher:
Total Pages: 0
Release: 2023
Genre:
ISBN:

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.

BTL Talks and Papers

BTL Talks and Papers
Author: Bell Telephone Laboratories, inc. Technical Information Libraries
Publisher:
Total Pages: 986
Release: 1977
Genre: Physics
ISBN: