Yves Marc Acremann


Last Name

Acremann

First Name

Yves Marc

ORCID

0000-0002-4109-3544

Organisational unit

03815 - Vaterlaus, Andreas / Vaterlaus, Andreas

Search Results

Publications 1 - 10 of 53
  • Magnetic pulser and sample holder for time- and spin-resolved photoemission spectroscopy on magnetic materials
    Item type: Journal Article
    Fognini, A.; Michlmayr, T. U.; Bähler, T.; et al. (2012)
    Review of Scientific Instruments
  • X-ray spectroscopy of current-induced spin-orbit torques and spin accumulation in Pt/3d-transition-metal bilayers
    Item type: Journal Article
    Stamm, Christian; Murer, Christoph; Acremann, Yves Marc; et al. (2019)
    Physical Review B
  • A time distribution system for single-shot experiments in the laboratory
    Item type: Journal Article
    Hecht, Linos; Ussling, Carl Frederic; Bozzini, Jingo; et al. (2025)
    Review of Scientific Instruments
    Amplified femtosecond laser systems offer sufficient pulse energy to study light-matter interaction with single-shot single-particle experiments. However, such event-based experimental approaches require combining multiple detectors that are read out for each individual laser pulse while preserving time synchronization. Consequently, it is crucial to reliably assign the recorded data from separate detectors to the same laser pulse. Here, we report on developing and implementing a time distribution system for a laboratory environment that adds a unique laser pulse identification number to the data stream of various detectors. In addition, it provides configurable low-jitter trigger pulses, which are distributed along the setup.
  • Nanoscale spin reversal by non-local angular momentum transfer following ultrafast laser excitation in ferrimagnetic GdFeCo
    Item type: Journal Article
    Graves, C. E.; Reid, A. H.; Wang, T.; et al. (2013)
    Nature Materials
  • X-ray spectroscopic identification of spin currents
    Item type: Conference Poster
    Stamm, Christian; Acremann, Yves Marc; Baumgartner, Manuel; et al. (2016)
  • 4D texture of circular dichroism in soft-x-ray photoemission from tungsten
    Item type: Journal Article
    Fedchenko, Olena; Medjanik, Katerina; Chernov, Sergey; et al. (2019)
    New Journal of Physics
    Photoemission-intensity distributions I RCP/LCP (E B , k ) measured for right- and left-circularly polarized soft x-rays revealed a large circular dichroism in angular distribution (CDAD) in the 4D parameter space (E B binding energy, k momentum vector). Full-field k-imaging combined with time-of-flight energy recording at a high-brilliance soft x-ray beamline allowed mapping the CDAD in the bulk Brillouin zone of tungsten and the entire d-band complex within a few hours. CDAD-asymmetries are very high (up to 90%), persist throughout the whole photon-energy range (300–1300 eV) and show a pronounced dependence on momentum k and binding energy E B, visualized as movies or sequences of cuts through the 4D object. One-step photoemission calculations for the same photon energies show fair agreement with the measured results. In addition to the requirement of a 'handed' experimental geometry, known from previous experiments on adsorbates and surface states, we find an anti-symmetric behavior of the CDAD with respect to two bulk mirror planes. A new symmetry condition along the perpendicular momentum kz makes CDAD a valuable tool for an unambiguous identification of high-symmetry planes in direct transitions in the periodic zone scheme. Technically, the method provides a circular polarimeter for soft, tender and hard x-rays.
  • Ultrafast magnetism: The magneto-optical Kerr effect and conduction electrons
    Item type: Journal Article
    Gort, Rafael; Bühlmann, Kevin; Saerens, Grégoire; et al. (2020)
    Applied Physics Letters
  • Compact setup for spin-, time-, and angle-resolved photoemission spectroscopy
    Item type: Journal Article
    Bühlmann, Kevin; Gort, Rafael; Fognini, Andreas; et al. (2020)
    Review of Scientific Instruments
    We present a compact setup for spin-, time-, and angle-resolved photoemission spectroscopy. A 10 kHz titanium sapphire laser system delivers pulses of 20 fs duration, which drive a high harmonic generation-based source for ultraviolet photons at 21 eV for photoemission. The same laser also excites the sample for pump-probe experiments. Emitted electrons pass through a hemispherical energy analyzer and a spin-filtering element. The latter is based on spin-polarized low-energy electron diffraction on an Au-passivated iridium crystal. The performance of the measurement system is discussed in terms of the resolution and efficiency of the spin filter, which are higher than those for Mott-based techniques.
  • Time- And momentum-resolved photoemission studies using time-of-flight momentum microscopy at a free-electron laser
    Item type: Journal Article
    Kutnyakhov, Dmytro; Bühlmann, Kevin; Däster, Simon; et al. (2020)
    Review of Scientific Instruments
    Time-resolved photoemission with ultrafast pump and probe pulses is an emerging technique with wide application potential. Real-time recording of nonequilibrium electronic processes, transient states in chemical reactions, or the interplay of electronic and structural dynamics offers fascinating opportunities for future research. Combining valence-band and core-level spectroscopy with photoelectron diffraction for electronic, chemical, and structural analyses requires few 10 fs soft X-ray pulses with some 10 meV spectral resolution, which are currently available at high repetition rate free-electron lasers. We have constructed and optimized a versatile setup commissioned at FLASH/PG2 that combines free-electron laser capabilities together with a multidimensional recording scheme for photoemission studies. We use a full-field imaging momentum microscope with time-of-flight energy recording as the detector for mapping of 3D band structures in (kx, ky, E) parameter space with unprecedented efficiency. Our instrument can image full surface Brillouin zones with up to 7 Å−1 diameter in a binding-energy range of several eV, resolving about 2.5 × 105 data voxels simultaneously. Using the ultrafast excited state dynamics in the van der Waals semiconductor WSe2 measured at photon energies of 36.5 eV and 109.5 eV, we demonstrate an experimental energy resolution of 130 meV, a momentum resolution of 0.06 Å−1, and a system response function of 150 fs.
  • The role of space charge in spin-resolved photoemission experiments
    Item type: Journal Article
    Fognini, Andreas; Salvatella, Gerard; Michlmayr, Thomas U.; et al. (2014)
    New Journal of Physics
    Spin-resolved photoemission is one of the most direct ways of measuring the magnetization of a ferromagnet. If all valence band electrons contribute, the measured average spin polarization is proportional to the magnetization. This is even the case if electronic excitations are present, and thus is of particular interest for studying the response of the magnetization to a pump laser pulse. Here, we demonstrate the feasibility of ultrafast spin-resolved photoemission using free electron laser (FEL) radiation and investigate the effect of space charge on the detected spin polarization. The sample is exposed to the radiation of the FEL FLASH in Hamburg. Surprisingly, the measured spin polarization depends on the fluence of the FEL radiation: a higher FEL fluence reduces the measured spin polarization. Space-charge simulations can explain this effect. These findings have consequences for future spin-polarized photoemission experiments using pulsed photon sources.
Publications 1 - 10 of 53