Article Atomic order induced reduction of Gilbert damping constant and enhancement of half-metallicity in off-stoichiometric Co2FeGa0.5Ge0.5 Heusler alloy thin films

Madhav M. Bhat ORCID ; K. Simalaotao SAMURAI ORCID (National Institute for Materials Science) ; H. Suto SAMURAI ORCID (National Institute for Materials Science) ; A. Perumal ; A. Srinivasan ; Y. Sakuraba SAMURAI ORCID (National Institute for Materials Science)

JAP_2025_Atomic order induced reduction of Gilbert damping constant and enhancement of half-metallicity in off-stoichiometric Co2FeGa0.5Ge0.5 Heusler alloy thin films.pdf
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Madhav M. Bhat, K. Simalaotao, H. Suto, A. Perumal, A. Srinivasan, Y. Sakuraba. Atomic order induced reduction of Gilbert damping constant and enhancement of half-metallicity in off-stoichiometric Co2FeGa0.5Ge0.5 Heusler alloy thin films. Journal of Applied Physics. 2025, 138 (4), 043904.

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(abstract)

The development of energy-efficient spintronic devices with enhanced magnetoresistance demands materials with low Gilbert damping constant (α) and high half-metallicity. In this study, we report a very low α in sputter-deposited off-stoichiometric Co2FeGa0.5Ge0.5 (CFGG) Heusler alloy thin films and investigate the relation between α and atomic ordering and half-metallicity. CFGG thin films with a composition of Co44.3Fe30.7Ga13.9Ge11.1 were epitaxially deposited on MgO (001) substrates by magnetron sputtering followed by in situ annealing. The density of states calculations revealed that this composition has higher half-metallicity than the stoichiometric composition, owing to Fermi energy tuning. As-deposited and 400 °C-annealed samples exhibited B2-type partially disordered structure, while annealing above 500 °C induced a L21-type ordered structure. The improvement in atomic order resulted in the reduction of α, as demonstrated by ferromagnetic resonance measurement, and enhancement in half-metallicity, as revealed by anisotropic and ordinary magnetoresistance measurements. The 600 °C-annealed samples exhibited an intrinsic α of (3.5 ± 0.3) × 10−4, the low value reported for metallic ferromagnetic materials, demonstrating the potential for its use in energy-efficient spintronic devices.

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Keyword: Spintronics, Heusler alloys, Ferromagnetic resonance,, Gilbert damping, Half-metallicity

Date published: 2025-07-28

Publisher: AIP Publishing

Journal:

  • Journal of Applied Physics (ISSN: 00218979) vol. 138 issue. 4 043904

Funding:

  • Core Research for Evolutional Science and Technology JPMJCR21O1
  • Advanced Storage Research Consortium
  • MEXT Initiative to Establish Next-generation Novel Integrated Circuits Centers JPJ011438

Manuscript type: Publisher's version (Version of record)

MDR DOI:

First published URL: https://doi.org/10.1063/5.0268776

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Updated at: 2025-10-28 09:04:43 +0900

Published on MDR: 2025-10-28 12:16:20 +0900

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