The XPS spectra for Fe, Cr, Ni, and Mo are presented in the SI8-1. Distinct peaks corresponding to Fe and Cr are observed, confirming their presence in the film. The Cr spectrum shows characteristic peaks at binding energies of 586.3 eV, 583.2 eV, 576.5 eV, and 573.7 eV, while the Fe spectrum exhibits peaks at 710.4 eV, 706.9 eV, 723.5 eV, and 719.7 eV. Additionally, the survey spectrum reveals a peak around 346 eV, which corresponds to the Ca 2p region, suggesting the presence of calcium. This calcium signal is most likely due to surface contamination. In contrast, the spectra for Ni and Mo do not show clear peaks, indicating that their signals are at or below the detection limit. The same observation can be made from the survey spectrum.