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arXiv · 1903.08285

Magnetic properties and domain structure of ultrathin yttrium iron garnet/Pt bilayers

Johannes Mendil·Morgan Trassin·Qingqing Bu·Jakob Schaab·Manuel Baumgartner·Christoph Murer·Phuong T. Dao·Jaianth Vijayakumar·David Bracher·Corinne Bouillet·Carlos A. F. Vaz·Manfred Fiebig·Pietro Gambardella
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Abstract

We report on the structure, magnetization, magnetic anisotropy, and domain morphology of ultrathin yttrium iron garnet (YIG)/Pt films with thickness ranging from 3 to 90 nm. We find that the saturation magnetization is close to the bulk value in the thickest films and decreases towards low thickness with a strong reduction below 10 nm. We characterize the magnetic anisotropy by measuring the transverse spin Hall magnetoresistance as a function of applied field. Our results reveal strong easy plane anisotropy fields of the order of 50-100 mT, which add to the demagnetizing field, as well as weaker in-plane uniaxial anisotropy ranging from 10 to 100 $\mu$T. The in-plane easy axis direction changes with thickness, but presents also significant fluctuations among samples with the same thickness grown on the same substrate. X-ray photoelectron emission microscopy reveals the formation of zigzag magnetic domains in YIG films thicker than 10 nm, which have dimensions larger than several 100 $\mu$m and are separated by achiral N\'{e}el-type domain walls. Smaller domains characterized by interspersed elongated features are found in YIG films thinner than 10 nm.

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Johannes Mendil, Morgan Trassin, Qingqing Bu, Jakob Schaab, Manuel Baumgartner, Christoph Murer, Phuong T. Dao, Jaianth Vijayakumar, David Bracher, Corinne Bouillet, Carlos A. F. Vaz, Manfred Fiebig, Pietro Gambardella. 2019-03-19. Magnetic properties and domain structure of ultrathin yttrium iron garnet/Pt bilayers. https://doi.org/10.1103/physrevmaterials.3.034403

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