Scientific Highlights
Crystallization of zirconia based thin films
In pulsed laser deposition the use of a rectangular or elliptical beam spot with a non 1:1 aspect ratio leads to the so called flip-over effect. Here, the longest dimension of the laser spot results in the shortest direction of plasma plume expansion.
Concept of a multichannel spin-resolving electron analyzer based on Mott scattering
The spin of electron plays a crucial role in many physical phenomena, ranging from the obvious example of magnetism, via novel materials for spintronics applications, to high-temperature superconductivity. Spin- and angle-resolved photoelectron spectroscopy (SARPES) gives the most direct access to the spin aspects of the electronic structure, but the one-channel detection principle of all presently available SARPES spectrometers severely limits their efficiency. A team of Swiss and Russian scientists has developed a revolutionary concept of a multichannel electron spin detector based on Mott scattering as the spin selective process and imaging-type electron optics.
Fermi Surface of Three-Dimensional La1−xSrxMnO3 Explored by Soft-X-Ray ARPES: Rhombohedral Lattice Distortion and its Effect on Magnetoresistance
A research team led by scientists from the Swiss Light Source has for the first time established three-dimensional (3D) electronic structure of the perovskite compound La1−xSrxMnO3 connected with its colossal magnetoresistance. Instrumental for this study has been the use of the new experimental technique of soft-x-ray ARPES, available at the ADRESS beamline, with its intrinsically sharp definition of 3D electron momentum.
Reduction of Mn19 Coordination Clusters on a Gold Surface
The surface-induced changes of the oxidation state and magnetic properties of Mn ion clusters have been probed by X-ray absorption spectroscopy and X-ray magnetic circular dichroism.
Mutual Independence of Critical Temperature and Superfluid Density under Pressure in Optimally Electron-Doped Superconducting LaFeAsO1−xFx
The superconducting properties of LaFeAsO1−xFx under conditions of optimal electron doping are investigated upon the application of external pressure up to ∼23 kbar. Measurements of muon-spin spectroscopy and dc magnetometry evidence a clear mutual independence between the critical temperature Tc and the low-temperature saturation value for the ratio ns/m* (superfluid density over effective band mass of Cooper pairs).
Spin-stripe phase in a frustrated zigzag spin-1/2 chain
In strongly correlated electron systems periodic modulations on the nano-scale have typically been associated with competition between short- and long-range interactions, for example, between exchange and dipole-dipole interactions in the case of ferromagnetic thin films. Here we show that spin-stripe textures may develop also in antiferromagnets, where long-range dipole-dipole magnetic interactions are absent.
Spin-stripe phase in a frustrated zigzag spin-1/2 chain
Motifs of periodic modulations are encountered in a variety of natural systems, where at least two rival states are present. In strongly correlated electron systems, such behaviour has typically been associated with competition between short- and long-range interactions, for example, between exchange and dipole-dipole interactions in the case of ferromagnetic thin films.
Controllable Broadband Absorption in the Mixed Phase of Metamagnets
Combination of neutron scattering, muon spin relaxation, specific heat, ac and dc magnetization measurements, and electron magnetic resonance, reveals the ability of metamagnetic materials to absorb the electromagnetic radiation in an extremely broad frequency range.
Catalytically Active and Spectator Ce3+ in Ceria-Supported Metal Catalysts
Using time-resolved resonant X-ray emission spectroscopy, we quantitatively correlated the initial rate of Ce3+ formation under transient conditions to the overall rate of CO oxidation under steady-state conditions and showed that ceria reduction is a kinetically relevant step in CO oxidation, whereas a fraction of Ce3+ was present as spectators.
Catalytically Active and Spectator Ce3+ in Ceria-Supported Metal Catalysts
Identification of active species and the rate-determining reaction steps are crucial for optimizing the performance of oxygen-storage materials, which play an important role in catalysts lowering automotive emissions, as electrode materials for fuel cells, and as antioxidants in biomedicine. We demonstrated that active Ce3+ species in a ceria-supported platinum catalyst during CO oxidation are short-lived and therefore cannot be observed under steady-state conditions.