## 4 Analytical Discussion
### Keywords Assessment
* Cluster 3: Sol-gel technology was preferred to synthesize YIG film due to its inexpensive cost, simple preparation, and easy material composition control. Sol-gel provides exceptional uniformity microstructure, high purity, and nanocrystalline material [140; 141]. In terms of optical properties, terbium- and aluminum-doped YIG films prepared by the sol-gel method were found to be between 76% and 92% transparent in the visible and infrared ranges [140]. According to the results reported by [PERSON] and [PERSON] [141], cerium-doped YIG films have exceptional qualities such as homogeneous structure, small nano grain size, high optical transparency (over 80%), and excellent magnetic properties. Having their best attributes, the films are more promising for use in magneto-optical devices. * Cluster 4: The discovery of yttrium iron garnet (YIG) led to amazing advancements in microwave technology more than 50 years ago. YIG is suitable for microwave applications such as filters or sensors due to its band gap of 2.66 eV, low magnetic damping, and soft magnetization characteristics, which makes it a good insulator [86]. [PERSON] et al. [72] developed configurable microwave-to-magnon transducers. Their solutions enabled integrating microwave electronics utilizing exchange-dominated spin-waves and improving magnonics-based technology. * Cluster 5: YIG is a well-studied ferrimagnetic insulator with a Curie temperature that is above room temperature (Tc = 550 K). It has been explored as a prototype magnetic insulator for spinning waves and magnonic physics, involving spin-Hall and spin-Seebeck effects [19]. * Cluster 6: [PERSON] et al. discovered that nanometer-thin films with thicknesses around 17 to 200 nm which are relatively close to the YIG bulk saturation moments at room temperature (135 emu cm) had low coercivity (<2 Oe) and low magnetic damping value as low as 2.2 \(\times\) 10\({}^{-4}\)[2]. These thin films are valuable for investigating the development of magnetization dynamics and innovative magnetic phenomena. From the analysis of the cluster keywords, researchers can perform a more in-depth evaluation of the references and/or publications recognized as important in each network cluster [142]. Keyword co-occurrence maps make it easy to observe the keyword analysis relationship; therefore, it helps in assessing YIG thin film research terms. However, as discussed in the clusters section, not all keywords in each cluster are utilized. There may be other discussions that correlate to the cluster's keywords. Nevertheless, in some instances, as indicated by [PERSON] et al. [143], it remains unclear why VOS viewer classified some keywords terms into the same category and established a new cluster rather than assigning them to other clusters with similar characteristics. This explanation must be investigated in future research. This work provides a thorough manual examination (using Microsoft Excel) of the most effective keywords that frequently appeared in the top 100 citation publications. Figure 7 shows the top 15 most utilized keywords in the top 100 cited articles. The larger font size in letter words represents YIG papers' most favorable keywords. It is discovered that the popular keywords in the last ten years are iron (frequency = 64), yttrium iron garnet (frequency = 59), garnets (frequency = 45), film (frequency = 29), temperature (frequency = 22), ferromagnetic (frequency = 19), magnetism (frequency = 17), spin-waves (frequency = 14), pulse laser deposition (frequency = 13), damping (frequency = 12), spin-Hall effect (frequency = 11), ferrimagnetic (frequency = 11), magneto-optical (frequency = 11), gadolinium gallium garnet (frequency = 8) and microwave (frequency = 7). This analysis demonstrates that prevalent interest was attracted to the keywords \"Iron\", \"yttrium iron garnet\", \"garnets\", \"film\" and \"temperature\".