Towards spin-polarized two-dimensional electron gas at a surface of an antiferromagnetic insulating oxide

Abstract

The surfaces of transition-metal oxides with the perovskite structure are fertile grounds for the discovery of novel electronic and magnetic phenomena. In this article, we combine scanning transmission electron microscopy (STEM) with density functional theory (DFT) calculations to obtain the electronic and magnetic properties of the (001) surface of a (LaFeO 3) 8 /(SrFeO 3) 1 superlattice film capped with four layers of LaFeO 3. Simultaneously acquired STEM images and electron-energy-loss spectra reveal the surface structure and a reduction in the oxidation state of iron from Fe 3+ in the bulk to Fe 2+ at the surface, extending over several atomic layers, which signals the presence of oxygen vacancies. DFT calculations confirm the reduction in terms of oxygen vacancies and further demonstrate the stabilization of an exotic phase in which the surface layer is half-metallic and ferromagnetic, while the bulk remains antiferromagnetic and insulating. Based on the calculations, we predict that the surface magnetism and conductivity can be controlled by tuning the partial pressure of oxygen.

Interface enhanced superconductivity in monolayer FeSe films on MgO(001): charge transfer with atomic substitution

“…In Fig. 2b, the L 3 and L 2 peak intensity ratio I(L 3 )/I(L 2 ), reflecting the valence state of Fe atoms [35], are also presented in blue. The ratio varies little (smaller than 4%) within the FeSe/FeTe films.…”

Enabling selective zinc-ion intercalation by a eutectic electrolyte for practical anodeless zinc batteries

“…The pre-peak in the O K edge is the result of electronic transitions from O 1 s states to O 2 p states. The O 2 p states are hybridized with the V 3 d states, and as a result, the higher O K edge pre-peak intensity points towards a higher number of empty O 2 p states hybridized with V 3 d states 49 , 50 . Therefore, the reduced intensity of the O K edge pre-peak is a direct result of V reduction upon Zn 2+ intercalation.…”

Amorphization and Plasticity of Olivine During Low‐Temperature Micropillar Deformation Experiments

“…We observe a prepeak at ~533 eV in the O K edge obtained from within the shear band, which is absent in the region away from it. The prepeak in the O K edge is attributed to electronic transitions from O 1 s core states to unoccupied O 2 p states that are hybridized to the empty states of neighboring atoms, specifically to the transition metal atoms (Luo et al, 2009; Mishra et al, 2016; Varela et al, 2009). A higher O K edge prepeak indicates a larger number of unoccupied O 2 p states hybridized to Fe 3 d states, which suggests a higher oxidation state of +3 for Fe.…”