Overall statement or summary of the article and its findings: The article mainly talking about the BFO-CFO heteroepitaxy having vertically aligned nanocomposite design. This design is unique because the BFO and CFO phases are self-assembly to forms a matrix and pillars, or vice versa depending upon their surface energy. Due to this fact, the authors conduct an in-depth study to reveal the phenomena by growing the BFO-CFO vertically aligned nanocomposite on different substrates. The article shows various experimental results such as XDR and AFM to reveal the structure of the samples. The authors also use magnetic measurement to understand the magnetic properties of the samples grown on different substrates. It shows that different strain states induced by the substrate on the BFO-CFO could change the shape and crystalline direction of CFO pillars which further reflect the magnetic properties. However, the strain-state from the substrate cannot change the role of surface energy in the formation of pillar-matrix of the constituent phases.

Overall strengths of the article and what impact it might have in your field: The article shows a clear explanation of the role of the strain state. In the formation of BFO-CFO vertically aligned nanocomposite, strain state is important to determine the architecture of BFO-CFO vertically aligned nanocomposite which further reflects the magnetic properties. This finding is important not only for theoretical studies about the formation of the vertically aligned nanocomposite. But also for searching for new nanocomposite materials based on vertically aligned nanocomposite for many practical applications.

Specific comments on weaknesses of the article and what could be done to improve it Major points in the article which needs clarification, refinement, reanalysis, rewrites and/or additional information and suggestions for what could be done to improve the article.
1. Required advance magnetic measurement because the changes of magnetic anisotropy could is not only related to the shape anisotropy of the CFO phase, but also the magnetic coupling with BFO phase
2. Raman spectroscopy could be used to reveal the strain state in the BFO-CFO vertically aligned nanocomposite more detail

Minor points like figures/tables not being mentioned in the text, a missing reference, typos, and other inconsistencies: 1. The figures are presented sufficiently, however, the numbers in the Figures somehow cannot be seen in detail because the size it small