Berlin 2012 – scientific programme

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MA: Fachverband Magnetismus

MA 15: Magnetization / Demagnetization Dynamics I

MA 15.11: Talk

Tuesday, March 27, 2012, 12:30–12:45, H 1012

Ultrafast Demagnetization by a Laser-Generated Hot Electron Pulse — •Christian Stamm, Andrea Eschenlohr, Niko Pontius, and Torsten Kachel — Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Str. 15, 12489 Berlin, Germany

Ultrafast demagnetization usually is triggered by a fs laser pulse. Here we demonstrate that a pulse of hot electrons is equally capable of causing a sizeable ultrafast demagnetization. We use a fs laser pulse to generate hot electrons in a 30 nm thick Au layer on top of a 15 nm Ni film. The laser pulse energy is absorbed to 90% in the Au, and hot electrons traveling from Au into the Ni film cause its magnetization to decrease down to 20% of the original value. The demagnetization time of the Au/Ni sample is slightly slower than the one of a Ni reference, but still in the fs range. This is in accordance with a superdiffusive transport mechanism for the hot electrons.