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Browsing by Author "Buchanan, Kristen, advisor"

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    Growth and characterization of ultra-low damping Co₂₅Fe₇₅ thin films
    (Colorado State University. Libraries, 2020) Swyt, Mitchell, author; Buchanan, Kristen, advisor; Ross, Kate, committee member; Menoni, Carmen, committee member
    This thesis focuses on the growth and characterization of ultra-low damping Co25Fe75 thin films. Ultra-low damping in a metal is of interest for the design of new spintronic devices because this offers the opportunity to move both electrons and spin waves over appreciable distances. In this work, the effects of seed and capping layers on the damping parameter and magnetization are investigated. A series of thin films were deposited using DC magnetron sputtering. A combination of X-ray reflectometry (XRR), vibrating sample magnetometry (VSM), and ferromagnetic resonance spectroscopy (FMR) were used to determine the film quality, saturation magnetization, and damping parameters of each film. The results show that the Ta seed layers promoted smooth film growth for Co25Fe75, but direct interfaces with Ta or Pt resulting in enhanced damping. Cu spacer layers can be used to disrupt the enhancement but promote rough film growth for the studied sample growth conditions. Damping values in agreement with published results were achieved for two films from the set, with α=0.0064 ± 0.0004 for Ta/Co25Fe75 and α=0.0063 ± 0.0011 for Ta/Cu/Co25Fe75/Cu/Ta.
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    Spin wave characterization in a 1D YIG magnonic crystal
    (Colorado State University. Libraries, 2023) Compton, Lia, author; Buchanan, Kristen, advisor; Harton, John, committee member; Prieto, Amy, committee member
    In this thesis, I will analyze and discuss features of spin wave propagation characteristics measured in a one-dimensional (1D) yttrium iron garnet (YIG) magnonic crystal using time-resolved Brillouin light scattering (TR-BLS) measurements. Magnonic crystals are a promising candidate to aid in developing spin-based devices that exploit the spin of the electron since magnonic crystals can be used to control the information transmitted by spin waves. In magnonic crystals, periodic modulation of the material properties is used to create a band structure and hence allow or suppress the propagation of spin waves with specific frequencies. To better understand spin wave propagation in a 1D YIG magnonic crystal, (TR-BLS) measurements were used to map out the temporal and spatial evolution of spin wave pulses at different frequencies. By analyzing the TR-BLS data with a cross-correlation method, the group velocities were determined at different frequencies and a better understanding of the changes in the pulse shape is gained. The TR-BLS data show that multiple width-quantized spin wave modes are present and highlights the importance of considering the two-dimensional nature of spin wave propagation, even in a one-dimensional system.