Berlin 2015 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 29: Spincaloric Transport II (jointly with TT)

MA 29.5: Vortrag

Mittwoch, 18. März 2015, 16:00–16:15, H 0110

Magnetic field dependence of magnon accumulation in ferromagnets — •Ulrike Ritzmann, Denise Hinzke, and Ulrich Nowak — Universität Konstanz, Konstanz, Germany

In the last years it was shown that in a magnetic material spin currents are created by applying temperature gradients. This spin currents are due to a net magnon current that propagates from the hotter towards to cooler region of the magnetic material [1].

We perform atomistic spin model simulation with the stochastic Landau-Lifshitz-Gilbert equation for different temperature profiles to study magnon accumulation and magnonic spin currents and its characteristic lengthscales in ferromagnetic insulators [2]. Furthermore, we present simulations regarding the magnetic field dependence of the magnon propagation in linear temperature gradients, which allow to control the excited spin current and tune the frequency spectra of the involved magnons. The results show an increasing signal with increasing length of the system with a saturating behavior in agreement with experimental measurements [3]. On the other hand, we study the magnetic field dependence of the magnon accumulation and find a decreasing accumulation for increasing magnetic field. Both effects can be explained with the frequency distribution of the propagating magnons that are excited in the temperature gradient and its dependence on the system parameters. We acknowledge financial support by the DFG through SFB 767 and through SPP "Spin Caloric Transport".

[1] K. Uchida et al., APL 97, 172505(2010); [2] Ritzmann et al., PRB 89, 024409 (2014); [3] Kehlberger et al., arXiv:1306.0784