Magnetic coupling in highly-ordered NiO/Fe3O4(110): Ultrasharp magnetic interfaces vs. long-range magnetoelastic interactions

We present a laterally resolved X-ray magnetic dichroism study of the magnetic proximity effect in a highly ordered oxide system, i.e. NiO films on Fe3O4(110). We found that the magnetic interface shows an ultrasharp electronic, magnetic and structural transition from the ferrimagnet to the antiferromagnet. The monolayer which forms the interface reconstructs to NiFe2O4 and exhibits an enhanced Fe and Ni orbital moment, possibly caused by bonding anisotropy or electronic interaction between Fe and Ni cations. The absence of spin-flop coupling for this crystallographic orientation can be explained by a structurally uncompensated interface and additional magnetoelastic effects

Demographic, clinical and antibody characteristics of patients with digital ulcers in systemic sclerosis: data from the DUO Registry

OBJECTIVES: The Digital Ulcers Outcome (DUO) Registry was designed to describe the clinical and antibody characteristics, disease course and outcomes of patients with digital ulcers associated with systemic sclerosis (SSc). METHODS: The DUO Registry is a European, prospective, multicentre, observational, registry of SSc patients with ongoing digital ulcer disease, irrespective of treatment regimen. Data collected included demographics, SSc duration, SSc subset, internal organ manifestations, autoantibodies, previous and ongoing interventions and complications related to digital ulcers. RESULTS: Up to 19 November 2010 a total of 2439 patients had enrolled into the registry. Most were classified as either limited cutaneous SSc (lcSSc; 52.2%) or diffuse cutaneous SSc (dcSSc; 36.9%). Digital ulcers developed earlier in patients with dcSSc compared with lcSSc. Almost all patients (95.7%) tested positive for antinuclear antibodies, 45.2% for anti-scleroderma-70 and 43.6% for anticentromere antibodies (ACA). The first digital ulcer in the anti-scleroderma-70-positive patient cohort occurred approximately 5 years earlier than the ACA-positive patient group. CONCLUSIONS: This study provides data from a large cohort of SSc patients with a history of digital ulcers. The early occurrence and high frequency of digital ulcer complications are especially seen in patients with dcSSc and/or anti-scleroderma-70 antibodies

Spektroskopie besetzter und unbesetzter Zustände intermetallischer Verbindungen mit Röntgenphotoemission und Bremsstrahlung-Isochromat-Spektroskopie

This thesis reports an extensive investigation of the electronic structure of intermetallic alloys. The experimental techniques used were X-ray photoemission and Bremsstrahlung isochromat spectroscopy (BIS). BIS was performed with a newly developed high current electron gun especially adapted to the geometry of Johann-type soft X-ray monochromators.-The combination of these two techniquesyields a complete picture of the electronic structure of a solid, both for the occupied and unoccupied states. Applying these methods to alloys of transition metals,one of which has a nearly full d-band, whereas the d-band of the other metal is nearly empty, led to a description of such alloys in terms of a molecular orbital picture : In analogy to the hydrogen molecule, the interaction between the two "d-states" leads to bonding and antibonding states which are narrower than, and slightly shifted with regard to the parent d-states, and a lowering of the density of states at the Fermi level. While the previous studies were concerned with the extended states in ametallic solid, a second set of experiments was aimed at elucidating the interaction between extended states and the localized 4f states of rare earths, and, in particular, Ce. BIS is very well suited to study this problem since in many cases the d-states of the transition metal ligands contribute only negligibly to the density of states above E F , whereas the contribution of the 4f states can be clearly recognized. The unoccupied 4f-states are drastically different for magnetic and nonmagnetic Ce compounds. Comparing with various other experiments one finds significant discrepancies, especially with regard to the average f occupation, which can only be caused by a sizeable hybridization between f-states and conduction states. Therefore, this hybridization is identified as the most important factor for the loss of magnetism in Ce intermetallics

Direct observation of electronic correlation in C60 by double photoemission

We report the first direct observation of electronic correlation for C-60 thin films on Cu by two-electron photoemission excited by a single photon. The energetic position of features associated with one step excitation of two electrons shows the influence of the electrostatic correlation energy between the two holes which are generated simultaneously on the same site. The correlation energy determined from this experiment for C-60 is 1.6 eV. The correlation energy is consistent with estimates derived from Auger spectroscopy

Core-valence interactions in Cr and Fe 2p photoemission

The magnetic linear dichroism (MLDAD) in Fe 2p photoemission spectra of an epitaxial ultrathin iron film has been determined. The experiment reveals multiplet related spectra, which allow a detailed characterization of the photoemission process in a simple final state model, that emphasizes the core-valence interaction in Fe 2p photoemission. The same model was used to describe the Cr 2p photoemission spectrum of Cr adsorbates on a Fe surface. The importance of the investigations for the discussion of the 2p photoelectron spectra of 3d metals is pointed out