Thin Fe2O3layers (44 and 55 nm) were deposited by pulsed excimer laser ablation on single‐crystal alumina (&agr;‐Al2O3) substrates heated at 675 °C. The ion beam mixing of these &agr;‐Fe2O3/&agr;‐Al2O3couples was carried out using 300 keV Kr3+ions at a fluence of 2×1016ions/cm2. The mixing effect was followed by Rutherford backscattering spectrometry (RBS), conversion electron Mo¨ssbauer spectroscopy, and grazing incidence x‐ray diffraction method. RBS spectra do not show any evidence of mixing at the interface, whereas the data obtained with the two other techniques display phases like oxygen deficient Fe3O4, Fe3−yAlyO4, and Fe1+xAl2−xO4. For this last phase,xis determined as being equal to about 0.5. It is shown that ion beam mixing is more efficient for the thinner Fe2O3layer, in accordance with the projected range of the Kr3+ions. ©1996 American Institute of Physics.