Distinctive Picosecond Spin Polarization Dynamics in Bulk Half Metals

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...

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Bibliographic Details
Published in:	Physical review letters 2018-08, Vol.121 (7), p.077205-077205, Article 077205
Main Authors:	Battiato, M, Minár, J, Wang, W, Ndiaye, W, Richter, M C, Heckmann, O, Mariot, J-M, Parmigiani, F, Hricovini, K, Cacho, C
Format:	Article
Language:	eng
Subjects:	Condensed Matter Electrons Femtosecond Iron oxides Materials Science Organic chemistry Physics Polarization (spin alignment) Spin dynamics Thermalization (energy absorption)
Online Access:	Get full text
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Summary:	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 Fe_{3}O_{4} 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.
ISSN:	0031-9007 1079-7114 1079-7114