| 1. |
- Kovalev, S., et al.
(författare)
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Selective THz control of magnetic order : new opportunities from superradiant undulator sources
- 2018
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Ingår i: Journal of Physics D. - : IOP Publishing. - 0022-3727 .- 1361-6463. ; 51:11
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Tidskriftsartikel (refereegranskat)abstract
- Recent advancements of accelerator technology enable the generation of carrier-envelope-phase stable THz pulses with high fields at adjustable high repetition rates. The appropriate choice of THz radiator allows generation of narrow-band, spectrally dense, multicycle THz transients of tunable THz frequency which are ideally suited to selectively excite low-energy excitations such as magnons or phonons. They also allow one to study the frequency dependence of nonresonant THz-field interactions with various order parameters with high dynamic range. In this paper, we discuss the future prospects of this new type of THz light source for studying the coherent control of magnetic order based on recent results.
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| 2. |
- Eichmann, U., et al.
(författare)
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Photon-recoil imaging : Expanding the view of nonlinear x-ray physics
- 2020
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Ingår i: Science. - : AMER ASSOC ADVANCEMENT SCIENCE. - 0036-8075 .- 1095-9203. ; 369:6511, s. 1630-1633
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Tidskriftsartikel (refereegranskat)abstract
- Addressing the ultrafast coherent evolution of electronic wave functions has long been a goal of nonlinear x-ray physics. A first step toward this goal is the investigation of stimulated x-ray Raman scattering (SXRS) using intense pulses from an x-ray free-electron laser. Earlier SXRS experiments relied on signal amplification during pulse propagation through dense resonant media. By contrast, our method reveals the fundamental process in which photons from the primary radiation source directly interact with a single atom. We introduce an experimental protocol in which scattered neutral atoms rather than scattered photons are detected. We present SXRS measurements at the neon K edge and a quantitative theoretical analysis. The method should become a powerful tool in the exploration of nonlinear x-ray physics.
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| 3. |
- Willems, F., et al.
(författare)
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Magneto-Optical Functions at the 3p Resonances of Fe, Co, and Ni : Ab initio Description and Experiment
- 2019
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Ingår i: Physical Review Letters. - : American Physical Society. - 0031-9007 .- 1079-7114. ; 122:21
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Tidskriftsartikel (refereegranskat)abstract
- We present experimental data and a complete theoretical description of the magneto-optical contributions to the complex refractive index in the extreme ultraviolet (XUV) range covering the 3p resonances of Fe, Co, and Ni. The direct comparison of the two allows us to conclude that many-body corrections to the ground state and local field effects are crucial for an accurate description of M-edge spectra. Our results are relevant for investigation of static magnetization, via XUV spectroscopy of multielement systems, as well as the dynamics of magnetization, as needed in the study of femtomagnetism and spintronics.
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| 4. |
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| 5. |
- Eisebitt, S, et al.
(författare)
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Electronic structure of single-wall carbon nanotubes studied by resonant inelastic X-ray scattering
- 1998
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Ingår i: APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING. - : SPRINGER VERLAG. - 0947-8396. ; 67:1, s. 89-93
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The electronic structure of single-wall nanotubes in "buckypaper" has been studied by using soft X-ray emission and resonant inelastic soft X-ray scattering. We observe electronic states derived from the K point and located close to E-F in the nanotubes,
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| 6. |
- Geilhufe, J., et al.
(författare)
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Extracting depth information of 3-dimensional structures from a single-view X-ray Fourier-transform hologram
- 2014
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Ingår i: Optics Express. - 1094-4087. ; 22:21, s. 24959-24969
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Tidskriftsartikel (refereegranskat)abstract
- We demonstrate how information about the three-dimensional structure of an object can be extracted from a single Fourier-transform Xray hologram. In contrast to lens-based 3D imaging approaches that provide depth information of a specimen utilizing several images from different angles or via adjusting the focus to different depths, our method capitalizes on the use of the holographically encoded phase and amplitude information of the object's wavefield. It enables single-shot measurements of 3D objects at coherent X-ray sources. As the ratio of longitudinal resolution over transverse resolution scales proportional to the diameter of the reference beam aperture over the X-ray wavelength, we expect the approach to be particularly useful in the extreme ultraviolet and soft-X-ray regime. (C) 2014 Optical Society of America
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| 7. |
- Pfau, Bastian, et al.
(författare)
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Influence of stray fields on the switching-field distribution for bit-patterned media based on pre-patterned substrates
- 2014
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 105:13
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Tidskriftsartikel (refereegranskat)abstract
- Using a direct imaging method, we experimentally investigate the reversal of magnetic islands in a bit-patterned media sample based on a pre-patterned substrate. Due to systematic variation of the island distances in the media, we are able to study the influence of the dipolar interaction on the switching-field distribution of the island ensemble. The experimental findings are explained by an analytical magnetostatic model that allows us to quantify the different components of the demagnetizing field in the system and to distinguish intrinsic and dipolar broadening of the switching-field distribution. Besides the well-known dipolar broadening due to stray fields from neighboring islands, we find strong influence from the magnetized trench material on the island switching. (C) 2014 Author(s).
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| 8. |
- Schmising, C. vonKorff, et al.
(författare)
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Nonlocal ultrafast demagnetization dynamics of Co/Pt multilayers by optical field enhancement
- 2015
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Ingår i: New Journal of Physics. - : IOP Publishing. - 1367-2630. ; 17
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Tidskriftsartikel (refereegranskat)abstract
- The influence on ultrafast demagnetization dynamics of metallic nano-structured gratings deposited on thin films of magnetic Co/Pt multilayers is investigated by the time-resolved optical Kerr effect. Depending on the polarization of the pump pulse, a pronounced enhancement of the demagnetization amplitude is found. Calculation of the inhomogeneous optical field distribution due to plasmon interaction and time-dependent solutions of the coupled electron, lattice, and spin temperatures in two dimensions show good agreement with the experimental data, as well as giving evidence of non-local demagnetization dynamics due to electron diffusion.
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| 9. |
- von Korff Schmising, C., et al.
(författare)
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Imaging Non-Local Magnetization Dynamics
- 2016
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Ingår i: Synchrotron Radiation News. - : Informa UK Limited. - 0894-0886 .- 1931-7344. ; 29:3, s. 26-31
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Tidskriftsartikel (refereegranskat)abstract
- Many fundamental processes in magnetism take place on a nanometer length and sub-picosecond time scale. An important example of such phenomena in magnetism is ultrafast, spin-polarized transport of laser-excited hot electrons, which is now being recognized as playing a crucial role for novel spintronic devices and for optically induced magnetic switching. Recent experimental examples include the demonstration of all-optical helicity dependent control of spin-polarized currents at interfaces [1], the design of novel and efficient terahertz emitters [2], and nanoscale spin reversal in chemically heterogeneous GdFeCo driven by non-local transfer of angular momentum [3]. In particular, for advanced information technologies with bit densities already exceeding 1 terabit per square inch with bit cell dimensions of (15 × 38 nm2) [4], it is of fundamental importance to understand and eventually control the mechanisms responsible for optically induced spin dynamics on the nanoscale.
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