Fe 2p absorption in magnetic oxides: Quantifying angular-dependent saturation effects

We show that the absorption spectra of magnetic iron oxides (Fe₃O₄, α-Fe₂O₃) exhibit strong angular-dependent saturation effects when measured in the total electron yield mode. We analyze quantitatively the impact of saturation by independent evaluations of the probing depth (d), the absorption length ({λ}), and their ratio (λ/d). Our estimates are d≈50, λ(L₃)=170, and λ(L₂)=525. The ratio λ(L₂)/d≈9 at the L₂ edge indicate that the extent of saturation is comparable to that observed in pure metallic Fe. In contrast, at the L₃ edge, saturation is considerably increased because of the reduced value of λ(L₃)/d≈3.5. As a consequence, quantitative magnetic studies based on linear and circular dichroism at the $2p$ edges of Fe in magnetic oxides must take into account and correct for saturation effects.