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Ultrathin ferrimagnetic GdFeCo films with very low damping

ORAL

Abstract

Spin-Hall nano oscillators (SHNOs) [1] have recently emerged as an alternative for microwave signal generation and bio-inspired oscillatory computing [2]. Due to their ultrafast magnetization dynamics with a ferromagnet-like spin-orbit-torque (SOT) behavior, there is a lot of interest in compensated ferrimagnets. For use in SHNOs, it is however important to ensure that such films retain their ferrimagnetic behavior also in ultrathin films. In this work, ferrimagnetic Gdx(FeCo)1-x thin films were grown on high resistance (HR) Si (100) substrates, and their magneto-dynamics was studied using ferromagnetic resonance measurements at room temperature. By tuning the stoichiometry, a nearly compensated behavior is for the first time demonstrated in 2 nm thin films. Values for the effective magnetization and effective Gilbert damping constant (α) of 0.02 Tesla and 0.0078 comparable to the lowest values obtained in thick films. In search of high-frequency auto-oscillations in SHNOs, constrictions with 50-300 nm widths were also prepared using Gdx(FeCo)1-x (2-10nm)/Pt(5nm) based stacks and Brillouin Light Scattering show SOT controllable ferromagnetic modes in these devices.

1. T. Chen et al, Proc. IEEE 104, 1919 (2016)

2. M. Zahedinejad et al., Nat. Nano. 15, 47–52 (2020).

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Presenters

  • Lakhan Bainsla

    Physics Department, University of Gothenburg

Authors

  • Lakhan Bainsla

    Physics Department, University of Gothenburg

  • Ahmad Awad

    Gothenburg University, Physics Department, University of Gothenburg

  • Akash Kumar

    University of Gothenburg, Physics Department, University of Gothenburg

  • Mohammad Zahedinejad

    1Physics Department, University of Gothenburg, 41296 Gothenburg, Sweden., Physics Department, University of Gothenburg

  • Nilamani Behera

    1Physics Department, University of Gothenburg, 41296 Gothenburg, Sweden., Physics Department, University of Gothenburg

  • Himanshu Fulara

    Indian Institute of Technology Roorkee, 1Physics Department, University of Gothenburg, 41296 Gothenburg, Sweden. 2Department of Physics, Indian Institute of Technology Roorkee, Roorkee 247667, India, Indian Institute of Technology Roorkee, India, Physics Department, University of Gothenburg

  • Roman Khymyn

    University of Gothenburg, Sweden, University of Gothenburg, Physics Department, University of Gothenburg, Physics Department, University of Gothenburg, 412 96 Gothenburg, Sweden

  • Afshin Houshang

    University of Gothenburg, 1Physics Department, University of Gothenburg, 41296 Gothenburg, Sweden., Physics Department, University of Gothenburg

  • Johan Åkerman

    Goteborg Univ, University of Gothenburg, 1Physics Department, University of Gothenburg, 41296 Gothenburg, Sweden., University of Gothenburg, Sweden, Physics Department, University of Gothenburg, Physics Department, University of Gothenburg, 412 96 Gothenburg, Sweden