Study of surface structure and interfacial effects on optical and magnetic properties of un-doped and Si-doped hematite films

[Display omitted] •Rhombohedral phase of hematite and Si-doped films deposited on SiO2/Si substrate.•Correlation between elemental profile and phase established using GI-XRD and RBS techniques.•Suppression of two-magnon mode and surface FM confirmed in Si-doped hematite film.•The films with low reflectivity, high refractive index (2.23–2.61) and optical band gap (2.30–3.68 eV) can be used for anti-reflecting glass.•The Si doped hematite films with soft ferromagnetism applicable in spintronics devices. Thermal evaporation technique has been used to synthesize the α-Fe2O3 (hematite) and Si-doped hematite films on three different substrates (SiO2/Si, Al2O3 and quartz). The post-deposition heat treatment at 800 °C has further improved the crystalline nature of the films. Rutherford backscattering spectroscopy has provided information for surface elemental composition and depth profile. Raman spectra have supported the formation of rhombohedral phase and inter-layer diffusion between substrate and films. The x-ray photoelectron spectroscopy has confirmed the mixed-valence oxidation states for Fe ions and +4 state for the Si ions in Si-doped hematite films. The optical reflectance spectra in the UV–Visible region indicated contributions from the films and film-substrate interface. The Si-doping has enhanced soft ferromagnetic properties in the hematite film with noticeable decrease of the magnetic coercivity and increase of the magnetic moment. The films showed blocking of magnetization at lower temperatures, typically below 125 K, and a wide thermomagnetic irreversibility between zero-field cooled and field cooled magnetization curves. The modified surface chemical structure, ferromagnetism and optical properties in the Si doped hematite films promise their potential applications in spintronics.