A Thin-Film Study of Iron/MgO Using Scattering Geometry of ⁵⁷Fe Mössbauer Spectroscopy

An experimental technique known as Conversion Electron Mössbauer Spectroscopy (CEMS) is built in our laboratory to study the surface properties of thin films prepared by Molecular Beam Epitaxial method (MBE). Pure Fe (30% enriched with ⁵⁷Fe) deposited on MgO substrate of 100 nm thickness is used to calibrate the CEMS system. The Zeeman spectrum and its intensity ratios of the spectral lines are analyzed in relation to the single crystal orientation. X-ray data of the thin film is correlated with this single crystal orientation and the easy axis of magnetization is determined. Comparison to the conventional transmission geometry is made for a polycrystalline sample of natural Fe absorber. The theory behind the magnetic dipole transition and the origin of the intensity Mössbauer lines are explained. Lorentzian line functions are used to obtain the least-squares fit of the experimental data.<br/><br/>This work is supported by the NSF PREM – Emergent Interface Materials, Grant 2122147.