Megahertz-rate ultrafast X-ray scattering and holographic imaging at the European XFEL.

The advent of X-ray free-electron lasers (XFELs) has revolutionized fundamental science, from atomic to condensed matter physics, from chemistry to biology, giving researchers access to X-rays with unprecedented brightness, coherence and pulse duration. All XFEL facilities built until recently provided X-ray pulses at a relatively low repetition rate, with limited data statistics. Here, results from the first megahertz-repetition-rate X-ray scattering experiments at the Spectroscopy and Coherent Scattering (SCS) instrument of the European XFEL are presented.

Increasing the Efficiency of a Spintronic THz Emitter Based on WSe/FeCo.

We report an increase in terahertz (THz) radiation efficiency due to FeCo/WSe structures in the reflection geometry. This can be attributed to an absorption increase in the alloy FeCo layer at the input FeCo/WSe interface due to constructive interference, as well as to the backward transport of hot carriers from FeCo to WSe. In contrast to the transmission geometry, the THz generation efficiency in the reflection is much less dependent on the magnetic layer thickness.

Polarization control of THz emission using spin-reorientation transition in spintronic heterostructure.

Polarization of electromagnetic waves plays an extremely important role in interaction of radiation with matter. In particular, interaction of polarized waves with ordered matter strongly depends on orientation and symmetry of vibrations of chemical bonds in crystals. In quantum technologies, the polarization of photons is considered as a "degree of freedom", which is one of the main parameters that ensure efficient quantum computing.

Photoinduced spin dynamics in a uniaxial intermetallic heterostructure [Formula: see text].

Intermetallic heterostructures of rare-earth and transition metals exhibit physical properties prospective for various applications. These structures combine giant magnetostriction, controllable magnetic anisotropy, magneto-optical activity and allow spin reorientation transitions (SRT) induced by magnetic field at room temperature. Here, we present the results of a study of spin dynamics induced by ultrafast optical excitation in the [Formula: see text] heterostructure.

Ultrafast magnetization dynamics in the vicinity of spin reorientation transition in TbCo/FeCo heterostructures.

The magnetic moment dynamics excited by 35 fs laser pulses in TbCo/FeCo heterostructure is experimentally investigated by pump-probe technique. The studies are carried out in two typical geometries with magnetizing field perpendicular and along to the easy magnetization axis. In the 'easy axis' orientation, high-frequency oscillations of magnetic moments odd with respect to the sign of the magnetizing field are observed using the magneto-optical Kerr effect.