Effect of growth rate on structural, magnetic and spin dynamic properties of Co2FeAl thin films

• Published in: Thin solid films 2024-03, Vol.792, p.140268, Article 140268
• Main Authors: Mondal, Rohiteswar, Devapriya, M S, Pradhan, Jhantu, Haldar, Arabinda, Murapaka, Chandrasekhar
• Format: Article
• Language: English
• Subjects: Cobalt–Iron–Aluminum thin film; Ferromagnetic resonance; Gilbert damping; Heusler alloy thin films; Spin dynamics; Sputtering
• ISSN: 0040-6090; 1879-2731
• DOI: 10.1016/j.tsf.2024.140268

•Demonstrations of composition tunability from a single stoichiometric target.•Relatively low coercive fields in accordance with variable growth rate.•Significantly low damping of 0.004 for films grown at room temperature.•Relatively high effective magnetization values strongly depend on growth rates. The growth of high-quality Heusler alloy thin films with low damping is essential for designing low-power spintronic devices. Here, we report a systematic investigation of the structural, magnetic, and spin dynamic properties of Co-based (Cobalt, Iron, Aluminum) Heusler alloy Co2FeAl thin films via growth rate variation in sputtering. We found close stoichiometry comparable with the sputtering target towards higher growth rates. However, the stoichiometry of the films is off from the target at relatively low growth rates. The change in stoichiometry can be understood from the variation in the sputtering yield of each element present in the alloy. Grazing incidence X-ray diffraction patterns show that the films with different compositions have the A2 structure. However, the crystallite size strongly depends on the composition. Magneto-optic Kerr effect hysteresis measurements show low coercivity for all the samples, indicating soft magnetic behavior. Spin dynamics study using ferromagnetic resonance reveals that the film with close stoichiometry with the target exhibits the lowest damping parameter, i.e., 0.00448. Our results demonstrate the importance of sputtering growth rate on the structural, elemental, and magnetic properties of Heusler alloy thin films for spintronic device applications.