Berlin 2018 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 11: Ultrafast magnetism II

MA 11.4: Vortrag

Montag, 12. März 2018, 15:45–16:00, EB 407

Magnetization reversal and demagnetization dynamics of Co/Pt multilayers with circularly polarized laser pulses — •Umut Parlak, Roman Adam, Seung-gi Gang, Moritz Plötzing, Daniel E. Bürgler, and Claus M. Schneider — Peter Grünberg Institut, PGI-6, Research Centre Jülich, 52425, Jülich, Germany

All-optical control of magnetization has attracted great interest since it allows magnetization reversal in the absence of applied magnetic fields. Recent studies showed that deterministic magnetization reversal requires accumulation of many pulses in ferromagnetic layers unlike the ferrimagnetic layers which can be switched with single pulses. We present a study of all-optical magnetization reversal of ferromagnetic [Co/Pt]_N multilayers as a function of varying beam parameters. The multilayers were illuminated by a femtosecond laser beam with a wavelength of 800 nm and a repetition rate between 0.01 and 1 kHz. Our results indicate that all-optical magnetization reversal in [Co/Pt]_N multilayers is helicity dependent and the helicity-induced reversal probability scales with the number of pulses per unit area. Single pulses have no effect on magnetism as long as the laser fluence is kept below the demagnetization threshold. For pulses above this threshold, we employed time resolved magneto-optical Kerr effect magnetometry and investigated the ultrafast demagnetization process under exposure of circularly polarized single pulses.