x-ray reflectivity data (points) with fittings (solid lines) for Si/SiO2/Pt(3 nm)/Co(0.6 nm)/AlO x (2 nm) oxidized during , as-deposited or [(a)] and annealed at [(b)], 300 [(c)], and [(d)]). The curves are shifted vertically for the sake of clarity.
Thermal annealing ( ) dependence of thicknesses Th for Pt/Co/AlO x samples oxidized during for the following layers: AlO x [top-left panel (a)], CoO [top-right panel (b)], Al [bottom-left panel (c)], and Co (for ) or CoPt alloy (for ) [bottom-right panel (d)].
Thermal annealing ( ) dependence of densities (ρ) for Pt/Co/AlO x samples oxidized during in the range (15-25-40-55) s for the following layers: AlO x (top part) and Al (inset) [top panel (a)], Co or CoPt alloy (top part), and CoO (bottom part) [bottom panel (b)]. Bulk values are added in straight lines.
Ratios of the thicknesses of AlO x , R(AlO x ) [top-left panel (a)] and Co, R(Co) [top-right panel (b)], calculated starting from parameters deduced from fittings of Fig. 1 , as a function of both the oxidation time and the annealing temperature for Pt/Co/AlO x samples. and are varied in the (15–60) s and (20–450) °C ranges, respectively. The vertical arrow is the oxidation time starting from the Al layer is fully oxidized, whereas a CoO layer appears. Map of the roughness rms σ of AlO x , σ(AlO x ) [bottom-left panel (c)] and Co, σ(Co or CoPt) [bottom-right panel (d)] for such samples, the scale being in nm. The lowest value of (20 °C) corresponds to the as-deposited sample.
Co-K edge XANES normalized profiles for as-deposited Pt/Co/AlO x trilayers and oxidized for different oxidation time . Note the evolutions of typical peaks [A (pre-edge), B (white line), and C] as a function of . Bulk references for Co and CoO are added for comparison. The 60 s is slightly shifted towards positive absorption for clarity of presentation (very close to the 55 s line).
Normalized white line area (left), corresponding to the normalized peak B appearing in Fig. 5 , and content of CoO deduced from ab initio simulations 40 (right) versus for as-deposited Pt/Co/AlO x trilayers. Inset: Example of integration of the white line (normalized intensity) for = 40 s with the values for the energy ( and ) and the minimal XANES normalized intensity ( ) used for calculating the areas.
Experimental (a) and simulated (b) Co-K edge XANES data for as-deposited Pt/Co/AlO x trilayers as a function of the oxidation time . Here, data are fitted with the help of FDMNES code 40 starting from a linear combination of calculated spectra for Co and .
Experimental (a)–(d) and simulated (e) Co-K edge XANES data for as-deposited Pt/Co/AlO x trilayers oxidized during different oxidation times [(a) 15 s; (b) 25 s; (c) 40 s; (d) 55 s], and annealed for different temperatures (300 °C and 450 °C).
Co-K edge XANES normalized profiles for as-deposited Pt/Co/AlO x trilayers, for in-plane and out-of-plane polarization geometries, and oxidized for [(a)] and 40 s [(b)]. Insets: Zoom of the Co-K edges. Note the differences for only , where the Co-oxygen bonds are reinforced for the out-of-plane configuration (see the arrows).
Co-K edge XANES normalized profiles for annealed Pt/Co/AlO x trilayers at = 300 °C, for in-plane and out-of-plane polarization geometries, and oxidized for = 15 s [(a)] and 40 s [(b)]. Insets: Zoom above the Co-K edges. Differences appear for : the contribution of Co-oxygen bonds is stronger for the out-of-plane configuration (see the arrows).
Crossover value (starting from a fully oxidized Al layer is obtained), thickness Th, and roughness σ for Co, CoPt, and AlO x layers as a function of deduced from fits’ parameters coming from adjustments of reflectivity data. CoPt is uniquely obtained for = 450 °C. Additional results are given for the sample elaborated for = 40 s and annealed at = 300 °C.
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