## 3 Results and Discussion
### Substrate Temperature Effects  
To investigate the effects of substrate temperature on the growth of this type of garnet film and on their optical and magneto-optical behaviors, we prepared four batches of samples, named S\({}_{\rm TI}\), S\({}_{\rm TI}\), S  
Figure 1: X-ray-generated energy dispersive spectroscopy (EDS) spectrum obtained for a garnet film deposited from a target of nominal stoichiometry Bi\({}_{2.1}\)Dy\({}_{0.9}\)Fe\({}_{3.9}\)Ga\({}_{1.1}\)O\({}_{12}\). cps: Count per second. and \(\mathrm{S_{T4}}\), using significantly different substrate temperatures, from room temperature (RT) to 600 \({}^{\circ}\)C, but keeping all other deposition process parameters constant (including the deposition run time). The film thicknesses were monitored using a microbalance quartz sensor during the garnet layer deposition process and later remeasured based on the fitting of the measured and modelled transmission spectra using in-house developed and validated Magnetic Photonic Crystal (MPC) analysis software [5] as well as the commercially available OptiLayer software ([[http://www.optilayer.com](http://www.optilayer.com)]([http://www.optilayer.com](http://www.optilayer.com))). The as-deposited garnet layers (which were amorphous in phase) from each batch were annealed using the same crystallization process (at 670 \({}^{\circ}\)C for 1 h) by using a conventional air-atmosphere oven annealing heat treatment applied just after the deposition process. Note that, after annealing, it was also found that the thicknesses of the films closely matched those measured directly by the quartz sensor. The thickness errors were less than \(\pm\)2%. The bismuth content, as derived from the EDS datasets, within all deposited films in all experiments conducted at different substrate temperatures and rotation rates varied between 1.75 and 1.9 formula units. The specific Faraday rotation and the optical absorption coefficients at 532 nm were determined to calculate the MO figures of merit in Figure 2. After annealing, it was observed that the samples prepared on quartz substrates at room temperatures showed better MO properties (the highest Faraday rotation and MO figure of merit, as summarized in Table 1) at the 532 nm wavelength, though all of the annealed garnet films had relatively high absorption coefficients at 532 nm. It has also been noted that the absorption coefficient increased at very high substrate temperature (e.g., 600 \({}^{\circ}\)C) in Figure 2b, consequently reducing the MO quality (figure of merit) of the garnet layers. However, the films deposited at a higher temperature showed comparatively lower coercive force values. The lowest coercive force, of about 100 Oe, was measured for films deposited at 300 \({}^{\circ}\)C. The XRD datasets in Figure 2c obtained from the annealed garnet layers deposited at different substrate temperatures show sharp and well-defined diffraction peaks, indicating good crystallinity of the materials synthesized. In addition, it can be seen clearly that comparatively stronger diffraction peak intensities were observed in films deposited at room temperature, and the peak intensities tended to become weaker with increasing substrate temperature. The higher peak intensities may relate to obtaining increased volumetric fraction of the crystalline garnet phase present in these samples, which can also be related to higher MO performance observed in samples deposited at room temperature. The elemental composition data, represented as measured element concentrations in atomic %, collected from the as-deposited garnet films prepared at different substrate stage temperatures are summarized in Figure 2d. The Bi content, compared with the nominal stoichiometry of the sputtering target, was found to vary, owing to the varying loss of Bi atoms during the film growth process, in all garnet samples. The exact ratio between Fe and Ga contents in terms of atom numbers per formula unit (f.u.) was also found to be slightly different from the ratio estimated.