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MA: Fachverband Magnetismus

MA 22: Magnetization Dynamics I

MA 22.7: Talk

Wednesday, April 2, 2014, 11:15–11:30, HSZ 401

Equilibration of Electron Temperatures and Chemical Potentials during Ultrafast Magnetization Dynamics — •Benedikt Y. Mueller and Baerbel Rethfeld — Department of Physics and Research Center OPTIMAS, University of Kaiserslautern, Germany

Exciting a ferromagnetic nickel film with an ultrashort laser pulse leads to a quenching of the magnetization on a subpicosecond timescale [1]. Since this discovery, several models for the microscopic mechanism have been proposed, for instance, spin-flip scattering [2,3,4] and superdiffusive transport [5]. Today it seems that both processes contribute to the demagnetization, depending on the sample properties. Easy-to-handle models are essential to predict dynamic properties of systems with increasing complexity. Exploiting insights from our analysis of the spin-resolved Boltzmann equation [2,4] we set up a model governed by the equilibration of temperatures and chemical potentials of spin-up and spin-down electrons. This opens the possibility to describe transport effects in parallel with spin-flip processes and allows for analytical predictions of the demagnetization dynamics.

[1] Beaurepaire et al., PRL 76, 4250 (1996)

[2] Mueller et al., PRL 111, 167204 (2013)

[3] Koopmans et al., NMAT 9, 259 (2010)

[4] Essert et al., PRB 84, 224405 (2011)

[5] Battiato et al., PRL 105, 027203 (2010)