1：Experimental Design and Method Selection:

The study uses chemical solution deposition (CSD) to grow Mn-Co-Ni-O thin films on SiO2/Si(100) substrates, with thickness varied by repeating spin-coating and heat-treating processes. Structural analysis is done via XRD and SEM, and optical properties are measured using spectroscopic ellipsometry (SE) with a four-phase model and dispersion functions (Tauc-Lorentz and triple Lorentz models).

2：Sample Selection and Data Sources:

Four film samples (S1 to S4) with thicknesses of 180 nm, 320 nm, 430 nm, and 600 nm are prepared by varying the number of coating layers (12, 20, 30, 40 layers). Samples are deposited on SiO2/Si(100) substrates.

3：List of Experimental Equipment and Materials:

Equipment includes a RigaKu D/MAX-2550 x-ray diffractometer (XRD), field-emission scanning electron microscopy (FESEM, Sirion 200), and spectroscopic ellipsometer (IRSE, SC620, Shanghai). Materials include tetra-hydrated acetates of Ni, Mn, and Co (purity N99%), glacial acetic acid, and SiO2/Si(100) substrates.

4：Experimental Procedures and Operational Workflow:

Acetates are mixed in a molar ratio (Mn:Co:Ni=

5：

6：

0.48), dissolved in glacial acetic acid to 0.4 mol/L, filtered, and spin-coated at 4000 rpm for 20 s. Each layer is heat-treated at 200°C and 400°C for 20 s, and crystallized at 600°C for 5 min. Thickness is measured by SEM. XRD is performed in θ-2θ configuration with Cu Kα radiation, SEM for morphology, and SE at incident angles of 50° and 60° in 300-1000 nm range.

7：48), dissolved in glacial acetic acid to 4 mol/L, filtered, and spin-coated at 4000 rpm for 20 s. Each layer is heat-treated at 200°C and 400°C for 20 s, and crystallized at 600°C for 5 min. Thickness is measured by SEM. XRD is performed in θ-2θ configuration with Cu Kα radiation, SEM for morphology, and SE at incident angles of 50° and 60° in 300-1000 nm range. Data Analysis Methods:

5. Data Analysis Methods: XRD data analyzed using Scherrer's formula for grain size. SE data fitted with Tauc-Lorentz and triple Lorentz models to derive optical constants (refractive index n, extinction coefficient k, dielectric function ε2). Non-stoichiometric factors calculated from lattice constants.