Berlin 2018 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 11: Ultrafast magnetism II
MA 11.6: Vortrag
Montag, 12. März 2018, 16:15–16:30, EB 407
Magnetization dynamics during FeRh phase transition investigated with Time-Resolved X-ray Photoemission Spectroscopy — •F. Pressacco1,2, V. Uhlir3, M. Gatti4,5, J. A. Arregi3, A. Bendounan6, F. Sirotti4,6, and W. Wurth2,7 — 1CUI, Hamburg — 2Dep. Physik CFEL Laser Science, Uni. Hamburg — 3CEITEC BUT, Czech Republic — 4LPMC, École Polytechnique, France — 5European Theoretical Spectroscopy Facility (ETSF) — 6Synchrotron SOLEIL, France — 7DESY Photon Science, Hamburg
Direct investigation of the electronic structure by time-resolved photoemission is a powerful tool to follow fast modifications of the physical properties of a system. Here we present a Time Resolved X-ray Photoelectron Spectroscopy (TR-XPS) study of the metamagnetic phase transition induced by femtosecond laser excitation in FeRh epitaxial layers. FeRh is a particularly interesting system due to a first-order phase transition taking place at ∼400 K from an antiferromagnetic phase to a ferromagnetic phase (FM), which induces strong modifications of the electronic structure. In particular we observe the formation of a sharp spin-polarized peak close to the Fermi edge. We have measured the appearance of the peak after a 50 fs laser excitation and followed the onset of the FM phase triggered by the optical pulse. Moreover, by comparing the extracted electronic temperature to the intensity of the FM peak, we could show that the FM phase persists at the surface also when the system is expected to be antiferromagnetic. Ab initio density functional theory calculations associate the structure at the Fermi level to Fe 3d empty states.