Dresden 2014 – scientific programme

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MA: Fachverband Magnetismus

MA 36: Spincaloric Transport II (jointly with TT)

MA 36.3: Talk

Thursday, April 3, 2014, 10:00–10:15, HSZ 04

Magnonic spin currents and the spin Seebeck effect — •Ulrike Ritzmann, Denise Hinzke, and Ulrich Nowak — Universität Konstanz

In ferromagnetic insulators spatial temperature gradients can lead to a magnon accumulation [1]. Furthermore, it was shown that the measured voltage of the longitudinal spin Seebeck effect increases with film thicknes, saturating on a characteristic length scale [2].

We perform atomistic spin model simulation with the stochastic Landau-Lifshitz-Gilbert equation to investigate the relevant length scales for magnon accumulation. Supported by an analytical description we first calculate the characteristic length scale of magnon propagation in the vicinity of a temperature step [3]. Then we explore magnon propagation in a linear temperature gradient and determine the mean propagation length of the magnons [2]. Our main finding is that the magnon accumulation at the cold end of the temperature gradient first increases with the the length scale of the temperature gradient and then saturates when reaching the length scale of the magnon propagation. These results can explain the saturation of the longitudinal spin Seebeck effect [2] and can help to understand recent measurements regarding the temporal evolution of the spin Seebeck effect [4].

[1] K. Uchida et al, Nat. Mater. 9, 894 (2010)

[2] A. Kehlberger et al.,arXiv:1306.0784

[3] U. Ritzmann et al., submitted

[4] M. Agrawal et al., arXiv:1309.2164