DiProI
DiProI beamline at FERMI@ElettraThe lensless Coherent Diffraction Imaging (CDI) technique has been developed significantly and is gaining time resolved potentials thanks to the advent of coherent and ultrashort pulses delivered by the X-ray free electron lasers (FEL). The shot-to-shot temporal and energy stability of the seeded-FEL pulses at Fermi@Elettra has opened extraordinary opportunities for CDI and in particular for Resonant Coherent Diffraction Imaging (R-CDI), overcoming some of the limitations imposed by the partial longitudinal coherence of the SASE-FELs.In addition, the multiple (linear and circular) polarization of Fermi-FEL pulses is an added value to explore specific contrast mechanisms, relevant to the spin and orbital sensitive electronic transitions. |
Ptychography with OAM beams
Light beams possessing orbital angular momentum (OAM) are characterized by distinctive amplitude and phase structures. We were able to investigate how such a peculiar illumination, combined with optical aberrations, enhances the quality of ptychographic images obtained at the FERMI FEL source.
Single shot 3D imaging
The 3D map of an isolated object is obtained impinging simultaneously with two “twin” EUV FEL pulses from different directions. This new technique was designed on DiProI taking advantage of novel data analysis algorithms developed in collaboration with the Scientific Computing Team (SciComp).
Magnetic and light vortices
Magnetic helicoidal dichroism is observed when an extreme ultraviolet vortex beam, carrying Orbital Angular Momentum (OAM), interacts with a magnetic vortex. Classical electromagnetic simulations predict this dichroism based on the interference of light OAM modes, populated after the interaction with the magnetic topology. 
Evolution of chiral magnetic domain walls
The chirality of Néel magnetic domain walls can be measured by x-ray circular dichroism in resonant magnetic scattering. Their ultrafast evolution is explained as an increase of the walls width and a reduction of the magnetization, due to a spin current of hot electrons passing from the domain through the domain walls. 
Faster chiral magnetic order recovery
Studying the ultafast dynamics of chiral spin structures (Skyrmions) stabilized by Dzyaloshinskii-Moriya interaction (DMI) after optical excitation, the observed recovery of the chiral magnetic order is faster than the average collinear domain magnetization. 
Diffractive fluence mapping
The FEL fluence spatial distribution on the target can be mapped by drilling customized diffraction gratings on the sample membrane, providing real space imaging of the beam spot at the sample plane. This can be used to properly align the sample on the beam focus and to recover the single shot intensity profile of the pulse used in the experiment. 
Multi-color magnetic imaging
Nanoscale magnetic domain networks in Co/Pt heterostructure are spatially resolved through coherent imaging with Fourier-transform holography. Irradiating the holographic sample at the same time with two harmonics of the FEL seed, at resonance with O and Pt respectively, two element specific images are retrieved at the same time. 
Mini-TIMER: four wave mixing with FEL transient gratings
Extreme ultraviolet four wave mixing have been demonstrated at the DiProI beamline producing a transient grating with 70 fs FEL pulses, split into two halves and recombined on the sample with a known delay, and probing it with a 100 fs ultraviolet pulse to produce a fourth signal beam. 
Ultrafast demagnetization dynamics
When an ultrashort optical laser pulse excites a magnetic material, it responds with an almost instantaneous reduction of its magnetization, followed by a slower recovery. This dynamics can be followed by time resolved magnetic holography, taking FEL images of samples excited by IR pulses. 
Holography with customizable reference
Fourier transform holography retrieves microscopic images encoding in the X-ray scattered wave the interference between a known reference and the sample. The presented algorithm allows reconstruction from customizable references that can be designed in order to optimize signal from each particular sample, overcoming the limitations of standard holography geometries.
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