scholarly journals Element-Specific Magnetization Dynamics of Complex Magnetic Systems Probed by Ultrafast Magneto-Optical Spectroscopy

2020 ◽  
Vol 10 (21) ◽  
pp. 7580
Author(s):  
Clemens von Korff Schmising ◽  
Felix Willems ◽  
Sangeeta Sharma ◽  
Kelvin Yao ◽  
Martin Borchert ◽  
...  
Keyword(s):  
Optical Spectroscopy ◽  
Extreme Ultraviolet ◽  
High Harmonic ◽  
Specific Magnetization ◽  
Magnetization Dynamics ◽  
Magnetic Systems ◽  
Linearly Polarized ◽  
Laser Facility ◽  
The One ◽  
Polarized Radiation

The vision to manipulate and control magnetism with light is driven on the one hand by fundamental questions of direct and indirect photon-spin interactions, and on the other hand by the necessity to cope with ever growing data volumes, requiring radically new approaches on how to write, read and process information. Here, we present two complementary experimental geometries to access the element-specific magnetization dynamics of complex magnetic systems via ultrafast magneto-optical spectroscopy in the extreme ultraviolet spectral range. First, we employ linearly polarized radiation of a free electron laser facility to demonstrate decoupled dynamics of the two sublattices of an FeGd alloy, a prerequisite for all-optical magnetization switching. Second, we use circularly polarized radiation generated in a laboratory-based high harmonic generation setup to show optical inter-site spin transfer in a CoPt alloy, a mechanism which only very recently has been predicted to mediate ultrafast metamagnetic phase transitions.

scholarly journals Tomographic reconstruction of circularly polarized high-harmonic fields: 3D attosecond metrology

2016 ◽  
Vol 2 (2) ◽  
pp. e1501333 ◽  
Author(s):  
Cong Chen ◽  
Zhensheng Tao ◽  
Carlos Hernández-García ◽  
Piotr Matyba ◽  
Adra Carr ◽  
...  
Keyword(s):  
Extreme Ultraviolet ◽  
Tomographic Reconstruction ◽  
High Harmonic ◽  
Polarized Light ◽  
Copper Surface ◽  
Photoelectron Spectra ◽  
Laser Fields ◽  
Circularly Polarized Light ◽  
Circularly Polarized ◽  
Linearly Polarized

Bright, circularly polarized, extreme ultraviolet (EUV) and soft x-ray high-harmonic beams can now be produced using counter-rotating circularly polarized driving laser fields. Although the resulting circularly polarized harmonics consist of relatively simple pairs of peaks in the spectral domain, in the time domain, the field is predicted to emerge as a complex series of rotating linearly polarized bursts, varying rapidly in amplitude, frequency, and polarization. We extend attosecond metrology techniques to circularly polarized light by simultaneously irradiating a copper surface with circularly polarized high-harmonic and linearly polarized infrared laser fields. The resulting temporal modulation of the photoelectron spectra carries essential phase information about the EUV field. Utilizing the polarization selectivity of the solid surface and by rotating the circularly polarized EUV field in space, we fully retrieve the amplitude and phase of the circularly polarized harmonics, allowing us to reconstruct one of the most complex coherent light fields produced to date.

scholarly journals Formation of Inverse Energy Flux in the Case of Diffraction of Linearly Polarized Radiation by Conventional and Generalized Spiral Phase Plates

Photonics ◽  
2021 ◽  
Vol 8 (7) ◽  
pp. 283
Author(s):  
Andrey Ustinov ◽  
Svetlana Khonina ◽  
Alexey Porfirev
Keyword(s):  
Energy Flux ◽  
Poynting Vector ◽  
Numerical Study ◽  
Longitudinal Component ◽  
Light Fields ◽  
Linearly Polarized ◽  
Linearly Polarized Radiation ◽  
Phase Plates ◽  
Spiral Phase ◽  
Polarized Radiation

Recently, there has been increased interest in the shaping of light fields with an inverse energy flux to guide optically trapped nano- and microparticles towards a radiation source. To generate inverse energy flux, non-uniformly polarized laser beams, especially higher-order cylindrical vector beams, are widely used. Here, we demonstrate the use of conventional and so-called generalized spiral phase plates for the formation of light fields with an inverse energy flux when they are illuminated with linearly polarized radiation. We present an analytical and numerical study of the longitudinal and transverse components of the Poynting vector. The conditions for maximizing the negative value of the real part of the longitudinal component of the Poynting vector are obtained.

scholarly journals Table-top extreme ultraviolet second harmonic generation

2021 ◽  
Vol 7 (21) ◽  
pp. eabe2265
Author(s):  
Tobias Helk ◽  
Emma Berger ◽  
Sasawat Jamnuch ◽  
Lars Hoffmann ◽  
Adeline Kabacinski ◽  
...  
Keyword(s):  
Second Harmonic Generation ◽  
Harmonic Generation ◽  
First Principles ◽  
Extreme Ultraviolet ◽  
Second Harmonic ◽  
High Harmonic ◽  
Electronic Structure Calculations ◽  
Free Electron Lasers ◽  
X Ray ◽  
Structure Calculations

The lack of available table-top extreme ultraviolet (XUV) sources with high enough fluxes and coherence properties has limited the availability of nonlinear XUV and x-ray spectroscopies to free-electron lasers (FELs). Here, we demonstrate second harmonic generation (SHG) on a table-top XUV source by observing SHG near the Ti M2,3 edge with a high-harmonic seeded soft x-ray laser. Furthermore, this experiment represents the first SHG experiment in the XUV. First-principles electronic structure calculations suggest the surface specificity and separate the observed signal into its resonant and nonresonant contributions. The realization of XUV-SHG on a table-top source opens up more accessible opportunities for the study of element-specific dynamics in multicomponent systems where surface, interfacial, and bulk-phase asymmetries play a driving role.

scholarly journals Full-field imaging of thermal and acoustic dynamics in an individual nanostructure using tabletop high harmonic beams

2018 ◽  
Vol 4 (10) ◽  
pp. eaau4295 ◽  
Author(s):  
Robert M. Karl ◽  
Giulia F. Mancini ◽  
Joshua L. Knobloch ◽  
Travis D. Frazer ◽  
Jorge N. Hernandez-Charpak ◽  
...  
Keyword(s):  
Functional Imaging ◽  
Extreme Ultraviolet ◽  
Imaging Techniques ◽  
High Harmonic ◽  
Three Dimensional ◽  
Dynamic Imaging ◽  
Significant Advance ◽  
Grand Challenge ◽  
Diffractive Imaging ◽  
Full Field

Imaging charge, spin, and energy flow in materials is a current grand challenge that is relevant to a host of nanoenhanced systems, including thermoelectric, photovoltaic, electronic, and spin devices. Ultrafast coherent x-ray sources enable functional imaging on nanometer length and femtosecond timescales particularly when combined with advances in coherent imaging techniques. Here, we combine ptychographic coherent diffractive imaging with an extreme ultraviolet high harmonic light source to directly visualize the complex thermal and acoustic response of an individual nanoscale antenna after impulsive heating by a femtosecond laser. We directly image the deformations induced in both the nickel tapered nanoantenna and the silicon substrate and see the lowest-order generalized Lamb wave that is partially confined to a uniform nanoantenna. The resolution achieved—sub–100 nm transverse and 0.5-Å axial spatial resolution, combined with ≈10-fs temporal resolution—represents a significant advance in full-field dynamic imaging capabilities. The tapered nanoantenna is sufficiently complex that a full simulation of the dynamic response would require enormous computational power. We therefore use our data to benchmark approximate models and achieve excellent agreement between theory and experiment. In the future, this work will enable three-dimensional functional imaging of opaque materials and nanostructures that are sufficiently complex that their functional properties cannot be predicted.

scholarly journals Electron quantum path control in high harmonic generation via chirp variation of strong laser pulses

2021 ◽  
Author(s):  
Stylianos Petrakis ◽  
Makis Bakarezos ◽  
Michael Tatarakis ◽  
Emmanouil Benis ◽  
Nektarios Papadogiannis
Keyword(s):  
Laser Pulse ◽  
Ultraviolet Light ◽  
Harmonic Generation ◽  
Extreme Ultraviolet ◽  
High Harmonic ◽  
High Harmonic Generation ◽  
Ultrafast Laser ◽  
Temporal Window ◽  
Electron Quantum ◽  
Extreme Ultraviolet Light

Abstract The quantum phases of the electron paths driven by an ultrafast laser in high harmonic generation in an atomic gas depends linearly on the instantaneous cycle-averaged laser intensity. Using high laser intensities, a complete single ionisation of the atomic gas may occur before the laser pulse peak. Therefore, high harmonic generation could be localized only in a temporal window at the leading edge of laser pulse envelope. Varying the laser frequency chirp of an intense ultrafast laser pulse, the centre, and the width of the temporal window, that the high harmonic generation phenomenon occurs, could be controlled with high accuracy. This way, both the duration and the phase of the electron trajectories, that generate efficiently high harmonics, is fully controlled. An accurate and robust method of spectral control and selection of the high harmonic extreme ultraviolet light from distinct quantum paths is experimentally demonstrated. Furthermore, a phenomenological numerical model enlightens the physical processes that take place. This novel approach of the electron quantum path selection via laser chirp is a simple and versatile way of controlling the time-spectral characteristics of the coherent extreme ultraviolet light with future applications in the fields of attosecond pulses and soft x-ray nano-imaging.

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