Regensburg 2016 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 18: Spincaloric Transport
(Joint session of MA and TT organized by MA)

TT 18.8: Vortrag

Montag, 7. März 2016, 17:00–17:15, H31

Thickness-dependent low-temperature enhancement of the spin Seebeck effect in YIG films — •Joel Cramer¹, Er-Jia Guo^1,2, Andreas Kehlberger¹, Christoph Schneider¹, Gerhard Jakob¹, and Mathias Kläui¹ — ¹Institut für Physik, Johannes Gutenberg-Universität Mainz, 55099 Mainz, Germany — ²Quantum Condensed Materials Division, Oak Ridge National Laboratory, TN 37830, Oak Ridge, USA

In ferromagnetic insulator (FMI)/normal metal (NM) bilayers the temperature dependence of the spin Seebeck effect (SSE) has been probed as a function of FMI thickness, different interfaces and detection materials [1, 2]. At low temperatures, an enhancement of the SSE signal is observed, including the appearance of a peak in the amplitude. This enhancement is more pronounced for thicker films and vanishes for film thicknesses below 600 nm. Furthermore, the temperature of the signal maximum strongly depends on the FMI thickness as well as on the FMI/NM interface. The thickness dependence can be well explained by considering a model of a magnon-driven SSE, which takes into account the frequency dependent propagation length of thermally excited magnons inside the bulk material. The NM dependence, however, indicates that previously neglected interface effects play a major role in the observed signal. In order to obtain a better understanding of the influence of the FMI/NM interface, transmission electron microscopy (TEM) measurements combined with elemental analysis (EELS) are performed. [1] A. Kehlberger et al. Phys. Rev. Lett. 115, 096602 (2015) [2] Er-Jia Guo et al. arXiv: 1506.06037