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Distinctive picosecond spin polarization dynamics in bulk half metals

DOI: 10.1103/PhysRevLett.121.077205 DOI Help

Authors: M. Battiato (Nanyang Technological University; Technische Universität Wien) , J. Minár (University of West Bohemia) , W. Wang (Linköping University) , W. Ndiaye (Université de Cergy-Pontoise) , M. C. Richter (Université de Cergy-Pontoise; SPEC—CNRS/UMR 3680) , O. Heckmann (Université de Cergy-Pontoise; SPEC—CNRS/UMR 3680) , J.-m. Mariot (Sorbonne Université, CNRS (UMR 7614); Synchrotron SOLEIL) , F. Parmigiani (Università degli Studi di Trieste; Elettra-Sincrotrone Trieste; Universität zu Köln) , K. Hricovini (Université de Cergy-Pontoise; SPEC—CNRS/UMR 3680) , Cephise Cacho (Diamond Light Source; Central Laser Facility, Rutherford Appleton Laboratory)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Physical Review Letters , VOL 121

State: Published (Approved)
Published: August 2018

Abstract: Femtosecond laser excitations in half-metal (HM) compounds are theoretically predicted to induce an exotic picosecond spin dynamics. In particular, conversely to what is observed in conventional metals and semiconductors, the thermalization process in HMs leads to a long living partially thermalized configuration characterized by three Fermi-Dirac distributions for the minority, majority conduction, and majority valence electrons, respectively. Remarkably, these distributions have the same temperature but different chemical potentials. This unusual thermodynamic state is causing a persistent nonequilibrium spin polarization only well above the Fermi energy. Femtosecond spin dynamics experiments performed on Fe3O4 by time- and spin-resolved photoelectron spectroscopy support our model. Furthermore, the spin polarization response proves to be very robust and it can be adopted to selectively test the bulk HM character in a wide range of compounds.

Journal Keywords: Magnetism; Ultrafast phenomena; Half-metals; Time & angle resolved photoemission spectroscopy

Subject Areas: Physics

Technical Areas: Theoretical Physics