Dear Foroogh Khodadadi

Have you tried the Raman Spectroscopy method? Because I know that Raman spectroscopy can identify the characteristic spectral features of magnetite and can detect even very small amounts of magnetite on a solid surface.

Kind Regard.

try AFM test

This is indeed not so easy to measure and specifically to distinguish from the other Fe oxides.

One option besides the ones already mentioned by others is obviously to use any probe that is sensitive to ferromagnetism, because the inverse spinel magnetite is ferromagnetic ( as opposed to haematite and wüstite which are not). Options here might be to use Lorenz e-microscopy.

Another option might lie in using electron backscatter diffraction (EBSD) in conjunction with a very low acc. voltage (only a few kV... try it out) because you want to be surface-sensitive.

Here you must be very careful, however, that you are using a sufficiently high number of Kikuchi lines ! Otherwise, you cannot distinguish between the cubic magnetite and the likewise cubic wüstite ( They both share the same Oxygen 2 minus FCC lattice ).

These experiments are quite difficult to do and you need a very experience EBSD operator.

I attach a few papers where we have tried to do that, Just as a rough first guidance.

Good luck.

Dear researchers,

Thank you so much for your time and help. I greatly appreciate it.

Good luck

Have you already tried Raman microspectroscopy?

How can the largest amount of work be accomplished in the shortest possible time?