Dimensionality induced enhancement of ferromagnetic spin order and ferroelectric polarization in Ga doped α-Fe2O3 thin films

Structural phase stabilization via Ba site doping with bivalent Sr, Ca and Zn ions and Fe site doping with trivalent Cr and Ga ions in the BaFe12O19 hexaferrite and its magnetic modification

“…However, low energy peak components sufficiently differ from the BE at ∼708-709 eV and 722-723 eV due to Fe 2+ 2p 3/2 and Fe 2+ 2p 1/2 states, respectively. 30 These rules out the divalent Fe 2+ state in our doped samples. A peak component at lower BE (∼709.62-709.86 eV and 723.31-723.76 eV for Fe 2p 3/2 and 2p 1/2 bands, respectively) indicates a partial overlapping (covalent character) of Fe 3d and O 2p orbitals, especially for Ca-doped sample.…”

“…The satellite peaks, energy difference (ΔE) between the first lines of the Fe 2p 3/2 and Fe 2p 1/2 doublets (range 13.12-13.94 eV), and the energy difference between subcomponents (Δε) in each doublet (range of 0.50-1.72 eV) confirm Fe ions mostly in the trivalent (+3) charge state. 30,36,50,51 The depressed satellites in Ca-doped sample suggest a large chemical disorder at the Fe sites, which may arise due to the multi-valence (+3, +2) states of Fe ions or fractional charge transfer between Fe ions via Fe +(3−δ) -O 2− -Fe +(2+δ) (0 ≤ δ ≤1) superexchange paths that lead to partially covalence character between Fe 3+ and O 2− orbitals. 53 Theoretically, Fe 2p 3/2 and 2p 1/2 bands can form 4 and 2 multiplets.…”