State-resolved ultrafast charge and spin dynamics in [Co/Pd] multilayers

Le Guyader, Loïc; Higley, Daniel J.; Pancaldi, Matteo; Liu, Tianmin; Chen, Zhao; Chase, Tyler; Granitzka, Patrick W.; Coslovich, Giacomo; Lutman, Alberto A.; Dakovski, Georgi L.; Schlotter, William F.; Shafer, Padraic; Arenholz, Elke; Hellwig, Olav; Lalieu, Mark M.; Koopmans, Bert; Reid, Alexander H.; Bonetti, Stefano; Stöhr, Joachim; Dürr, Hermann A.

doi:10.1063/5.0076953

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State-resolved ultrafast charge and spin dynamics in [Co/Pd] multilayers

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Abstract

We use transient absorption spectroscopy with circularly polarized x rays to detect laser-excited hole states below the Fermi level and compare their dynamics with that of unoccupied states above the Fermi level in ferromagnetic [Co/Pd] multilayers. While below the Fermi level, an instantaneous and significantly stronger demagnetization is observed, above the Fermi level, the demagnetization is delayed by 35 ± 10 fs. This provides a direct visualization of how ultrafast demagnetization proceeds via initial spin-flip scattering of laser-excited holes to the subsequent formation of spin waves.

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72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS Charge dynamics Femtosecond lasers Ferromagnetic materials Microchannel plate detectors Spin-orbit interactions Spintronics Transient-absorption spectroscopy Ultrafast pump probe spectroscopy X-ray absorption spectroscopy X-ray magnetic circular dichroism spectroscopy

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Le Guyader, Loïc, Higley, Daniel J., Pancaldi, Matteo, Liu, Tianmin, Chen, Zhao, Chase, Tyler, Granitzka, Patrick W., Coslovich, Giacomo, Lutman, Alberto A., Dakovski, Georgi L., Schlotter, William F., Shafer, Padraic, Arenholz, Elke, Hellwig, Olav, Lalieu, Mark M., Koopmans, Bert, Reid, Alexander H., Bonetti, Stefano, Stöhr, Joachim, Dürr, Hermann A.. 2022-01-18. State-resolved ultrafast charge and spin dynamics in [Co/Pd] multilayers. https://doi.org/10.1063/5.0076953

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