Dresden 2014 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 29: Magnetization Dynamics II

MA 29.5: Vortrag

Mittwoch, 2. April 2014, 16:00–16:15, HSZ 401

Ultrafast relaxation dynamics of majority and minority electrons in ferromagnetic metals — Benedikt Y. Mueller, Mirko Cinchetti, Martin Aeschlimann, Hans Christian Schneider, and •Baerbel Rethfeld — Department of Physics and Research Center OPTIMAS, University of Kaiserslautern, Germany

It is experimentally well established that irradiating ferromagnetic films with an ultrashort laser pulse leads to a quenching of the magnetization on a subpicosecond timescale [1]. Currently, Elliott-Yafet like spin-flip processes [2,3,4] as well as superdiffusive transport [5] are discussed to cause this effect. Recently, we have shown that the Elliott-Yafet process, including its possibility during electron–electron collisions [3], can quantitatively reproduce ultrafast magnetization dynamics [4]. This is due to a feedback effect: The interplay of the equilibration of chemical potentials and temperatures and a dynamical exchange splitting increases the demagnetization considerably. In this talk we show additional insights how distinct collision processes influence magnetization dynamics. The Boltzmann description allows to switch separate collisions on and off, identifying their microscopic role on the dynamics. We further present the development of transient spin-resolved temperatures, chemical potentials and electronic energies.

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

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

[3] Krauss et al., PRB 80, 180407(R) (2009)

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

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