Yazar "Hindmarch, A. T." seçeneğine göre listele

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    Spin orbit torque driven magnetization reversal in CoFeTaB/Pt probed by resonant x-ray reflectivity
    (Amer Physical Soc, 2022) Burn, D. M.; Fan, R.; Inyang, O.; Tokac, M.; Bouchenoire, L.; Hindmarch, A. T.; Steadman, P.
    Resonant soft-x-ray reflectivity and vibrating sample magnetometry have been used to characterize field driven and spin orbit torque driven magnetization reversal in a CoFeTaB/Pt bilayer. Reversal of the magnetization occurs either along the applied field direction or perpendicular to the current flow direction. Magnetometry results show that field driven (current driven) coercivities are reduced by application of a current (field) highlighting the roles played by the two external parameters. In the current switching case, it is demonstrated with soft-x-ray hysteresis loops that only the layers near the interface with Pt switch, possibly highlighting the role of proximity effects of the magnetized Pt. We show how magnetization reversal perpendicular to the beam results in hysteresis behavior in the reflected intensity that is dependent on the magnetization but independent of the helicity of the circular polarization of the incident beam.
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    Temperature dependence of magnetically dead layers in ferromagnetic thin-films
    (Amer Inst Physics, 2017) Tokaç, Mustafa; Kinane, Christian J.; Atkinson, Darryn; Hindmarch, A. T.
    Polarized neutron reflectometry has been used to study interface magnetism and magnetic dead layers in model amorphous CoFeB: Ta alloy thin-film multilayers with Curie temperatures tuned to be below room-temperature. This allows temperature dependent variations in the effective magnetic thickness of the film to be determined at temperatures that are a significant fraction of the Curie temperature, which cannot be achieved in the material systems used for spintronic devices. In addition to variation in the effective magnetic thickness due to compositional grading at the interface with the tantalum capping layer, the key finding is that at the interface between ferromagnetic film and GaAs(001) substrate local interfacial alloying creates an additional magnetic dead-layer. The thickness of this magnetic dead-layer is temperature dependent, which may have significant implications for elevated-temperature operation of hybrid ferromagnetic metal-semiconductor spintronic devices. (C) 2017 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).
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    Threshold interface magnetization required to induce magnetic proximity effect
    (Amer Physical Soc, 2019) Inyang, O.; Bouchenoire, Laurence; Nicholson, Bruce; Tokaç, Mustafa; Rowan-Robinson, Richard; Kinane, Christian; Hindmarch, A. T.
    Proximity-induced magnetization (PIM) has broad implications across interface-driven spintronics applications employing spin currents. We directly determine the scaling between PIM in Pt and the temperature-dependent interface magnetization in an adjacent ferromagnet (FM) using depth-resolved magnetometry. The magnetization due to PIM does not follow the generally expected linear scaling with the FM interface magnetization, as a function of temperature. Instead, it vanishes while the FM interface magnetization remains. The effective magnetic susceptibilities of heavy-metal (HM) layers are shown to give rise to the previously unexplained asymmetric PIM found in HM/FM/HM trilayers.
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    Two Magnon Scattering Contribution to the Ferromagnetic Resonance Linewidth of Pt(Ir)/CoFeTaB/Ir(Pt) Thin Films
    (Springer Wien, 2023) Tokac, M.; Kazan, S.; Ozkal, B.; Al-jawfi, N.; Rameev, B.; Nicholson, B.; Hindmarch, A. T.
    The magnetic properties of Pt/CoFeTaB/Ir and Ir/CoFeTaB/Pt trilayer thin films have been studied using angular- and temperature-dependent ferromagnetic resonance. This enables quantitative determination of the various contributions to the magnetic behavior, including separating, the effective Gilbert damping, inhomogeneous damping, and two-magnon-scattering contributions to the magnetic dissipation. As-deposited films show behavior consistent with significant incorporation of Ir into CoFeTaB only when the Ir layer is deposited first. Annealing of the structures at 300 circle C\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$300\,<^>{\circ } \hbox {C}$$\end{document} causes only minor structural and magnetic modification when Pt is deposited first, and more pronounced changes, attributed to thermally-driven out-diffusion of Ir from CoFeTaB, are found when Ir is deposited first. A holistic consideration of the magnetic resonance behavior can provide detailed information on the atomic-scale structure in magnetic thin-film devices.