Static and Dynamic Magnetic Properties of FeGa/FeNi (FeNi/FeGa) Bilayer Structures

Round 1

Reviewer 1 Report

The authors presented results on magnetic properties of bilayer FeNi/FeGa structures on ITO substrates. I found the work interesting, however, I would like to draw the authors' attention to the following concenrs:

1. The language requires major editing, especially Introduction and Morphology paragraphs, which are not clear.
2. In the Introduction, the authors need to clarify the aim of their work, and especially the idea behind sputtering bilayer structures with only two different deposition times. Is there any special justification for using 200 and 500 s of the sputtering? After all, is there any specific reason for coupling that structure with ITO?
3. Fig. 1 shows XRD patterns of the samples under study, but I doubt how is it possible that the peak at ~35 deg (presumably ITO(400)) is the strongest once it should be that at ~30 deg (222). Apart from that, it is strange that sputtered FeNi and FeGa layers contributing to ca. 600 nm thick film exhibit such weak peaks relative to ITO. I think it is because of their large amorphicity. I suggest determining the size of CDD domains using the Williamson-Hall plot.
4. It might be good to present any comparison of the obtained results in terms of the order and the thickness of each layer. Which one is optimal and why? Are there any significant changes in the properties? What is basic physical mechanism behind that?

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

The authors have described the magnetic properties of FeGa/FeNi bilayer structures on ITO substrate prior to the high frequency applications. This work is well written and should be suitable for the acceptance in MDPI Coatings after minor corrections.

1. In this work, bilayer heterostructure was deposited via electrodeposition on ITO substrate but as mentioned, prior to the applications, these structures should be deposited on flexible substrate. The author should explain these difficulties.
2. The authors should mention from which supplier the chemicals are ordered.
3. The authors are encouraged to make a table from these line 76-78. Is there a link between deposition time and bilayers thickness? If yes, please mention this in the manuscript.
4. It is a pity that the SEM images on Figure 2 show poor resolution. How was cross-sectional view images made ? On these images, the several layers are visible, can the authors indicate them? Can the authors highlight the columnar structures on SEM images. It seems that the size are different. The authors can take the size distribution of columnar structures into the account for the comparison of the magnetic properties.
5. Line 145: The explanation of the abbreviation of FMR.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 3 Report

The authors investigated structure, morphology, static and dynamic magnetic properties of FeGa/FeNi films. The study shows that the bilayer structures exhibit extremely various magnetic properties with different deposition order. Specifically, the bilayer structures with FeGa on top show lower coercivity and their ferromagnetic resonance peak moves to high field compared to those with FeNi on top. These properties make FeGa/FeNi bilayer structures to be a potential candidate for the high frequency application. The work is interesting and can be published in Coatings if the following issues can be addressed:

1. The authors should cite the papers “Strong, lightweight, and highly conductive CNT/Au/Cu wires from sputtering and electroplating methods” (Journal of Materials Science & Technology, 2020, 40, 99-106) and “High-performance carbon fiber/gold/copper composite wires for lightweight electrical cables” (Journal of Materials Science & Technology, 2020, 42, 46-53) in the introduction section for better reviewing the metal coating by electrodeposition method.
2. Why do the bilayer structures need to be deposited on ITO substrate in this study? Can other substrates (ex: flexible substrate) be used instead?
3. Why does the surface of FeNi in Figure 2a, c, and e have different granular sizes while the surfaces of FeGa in Figure 2b, d, and f does not?
4. Can the authors explain more clearly how the different coupling interaction between FeNi and FeGa layers affects the results of dynamics magnetism of the bilayer structures?
5. The authors mentioned that “Because using electrodeposition method, many defects and high roughness are formed for the films, which may cause the magnetic properties different from sputtering or other preparation methods. Moreover, the defects and roughness can induce large damping coefficient.” Can the authors provide data showing the defects formed in the bilayer structures in this study?

Author Response

Please see the attached file

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

I feel satisfied with the changes the authors have made to their manuscript. No other concerns from my side.

Enjoy doing science!