We investigated the adsorption and reaction of pyridine on flat Pt(111) and stepped Pt(355) surfaces via high-resolution in situ x-ray photoelectron spectroscopy. The surfaces were exposed to pyridine at temperatures between 112 and 300 K while simultaneously recording XP spectra. Subsequently, the crystals were annealed and the temperature dependencies of the N 1s and C 1s core levels were studied again in a continuous and quantitative way. Various surface species were found, namely, physisorbed, flat-lying and end-on pyridine, α-pyridyl species on the terraces and on the steps and several unidentified high temperature species. We were able to show an influence of the steps of Pt(355) by pre-adsorbing silver next to the step, which selectively suppresses the step adsorption.

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Different layer thicknesses of Cobalt ranging from 2.6Å (1.5 ML) up to 55Å (30.5 ML) deposited on ferroelectric BaTiO3 have been studied regarding their magnetic behavior. The layers have been characterized using XMCD spectroscopy at remanent magnetization. After careful data analysis the magnetic moments of the Cobalt could be determined using the sum rule formalism. There is a sudden and abrupt onset in magnetism starting at thicknesses of 9Å (5 ML) of Cobalt for measurements at 120 K and of 10Å (5.5 ML) if measured at room temperature. Initial island growth and subsequent coalescence of Co on BaTiO3 is suggested to explain the sudden onset. In that context, no magnetically dead layers are observed.

The growth and magnetic properties of ultrathin iron oxide films on BaTiO3(001) substrate have been studied by low energy electron diffraction, x-ray absorption spectroscopy (XAS), x-ray magnetic circular dichroism (XMCD), and magneto-optic Kerr effect experiments. The iron oxide films were prepared by both simultaneous oxidation and postgrowth oxidation methods. Assuming a surface structure close to Fe3O4[100], the unit cell was found to be epitaxially grown on BaTiO3[100] unit cell due to small lattice mismatch between the film and the substrate. The films exhibit a uniaxial magnetic anisotropy with the easy-axis along Fe3O4[11¯0] direction. For the films on or above 1.7 nm thickness, the XMCD shows characteristic contributions from different Fe site occupations similar to those of the bulk Fe3O4. On the other hand, the XAS line shape and XMCD of the films in the thickness range 1.2–1.6 nm indicate the lesser occupation of Fe2+ octahedral sites associated with the formation of γ-Fe2O3 phase at lower thicknesses. Our investigations offer further insight into the structure, interface, and magnetic properties of the Fe3O4/BaTiO3 as an interesting system for technological applications.

High-quality epitaxial LaMnO 3 /LaAlO 3 superlattices (SLs) with (0 0 1), (0 1 1), and (1 1 1) out-of-plane orientation were grown by pulsed laser deposition. This SL material was predicted theoretically as a Chern insulator for realizing the quantum anomalous Hall effect. In our investigations, a paramagnetic-ferromagnetic phase transition is found with decreasing temperature around 100 K, indicating a controllable ferroic order at low temperatures. Electrical transport measurements reveal a thermally activated single-gap behavior with a fitted band gap of 436 meV for the (1 1 1)-oriented SL. With that, the results prove the predictions of a ferromagnetic background in the SLs, and of a gapped band structure.