Magnon transport in three-terminal YIG/Pt nanostructures studied by dc and ac detection techniques*

Magnon-mediated spin currents provide novel routes for spin transport and spin-based information processing. In our experiments, we deposit three electrically isolated platinum (Pt) strips on top of an yttrium iron garnet (YIG) thin film. The outer Pt strips act as spin current injector (source) and detector (drain). The center strip (gate) is utilized to modulate the magnon transport via an applied charge current. In the injector and modulator the charge current flow controls the magnon density in YIG via both the spin Hall effect and Joule heating. We compare two measurement schemes, a dc-technique utilizing the current reversal method and an ac-technique based on lock-in detection. We demonstrate that both techniques are well suited to investigate incoherent magnon transport in these three-terminal devices. However, while at low modulator charge current both schemes yield quantitatively identical results, we find clear differences above a certain threshold current. This allows us to get access to higher order terms originating from the injector current [1].
[1] J. Gückelhorn et al., arXiv, 2008.01416 (2020).