Regensburg 2019 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 2: Ultrafast magnetization effects and magnetization dynamics

MA 2.3: Vortrag

Montag, 1. April 2019, 10:00–10:15, H37

Magnetization dynamics due to femtosecond spin current pulses — •Karel Carva1, Pavel Baláž1, Ulrike Ritzmann2, Pablo Maldonado2, and Peter M. Oppeneer21Charles University, DCMP, Ke Karlovu 5, CZ-12116, Prague, Czech Republic — 2Uppsala University, PO Box 516, 75120 Uppsala, Sweden

Ultrafast demagnetization induced by femtosecond lasers is accompanied by spin current pulses, which arise and decay on timescales unprecedent in spintronics. These originate from migration of nonequilibrium hot charge carriers in a magnetic layer excited to bands with higher mobilities by a laser [1]. These spin currents may exert torque on adjacent perpendicularly oriented magnetic layers [2]. First we calculate this torque, and model the magnetization dynamics described by the Landau-Lifshitz-Gilbert equation within macrospin appproach. We also find an optimal thickness of the excited layer that maximizes the torque [3].

Since the perturbation of magnetization is localized on the scale of several nm [4], we also perform a more accurate atomistic spin dynamics simulations to study the magnon dynamics induced by the spin current. In particular we investigate the induced magnon population, its subsequent temporal evolution on ps timescale, and the formation of standing waves in confined systems.

[1] M. Battiato, K. Carva, P.M. Oppeneer, PRL 105, 027203 (2010)

[2] A.J. Schellekens et al., Nat. Comm. 5, 4333 (2014)

[3] P. Baláž et al., J. Phys.: Cond. Matter 30, 115801 (2018)

[4] I. Razdolski et al., Nat. Comm. 8, 15007 (2017)

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