Topological Hall effect at above room temperature in heterostructures composed of a magnetic insulator and a heavy metal

Shao, Qiming; Liu, Yawen; Yu, Guoqiang; Kim, Se Kwon; Che, Xiaoyu; Tang, Chi; He, Qing; Tserkovnyak, Yaroslav; Shi, Jing

doi:10.1038/s41928-019-0246-x

Cited by 131 publications

(135 citation statements)

References 41 publications

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“…The observed effect does not change with different adhesion layers [37], which indicates that the DMI does not originate from the top but from the bottom surface of YIG consistent with TmIG/GGG samples reported recently [19][20][21]. The DMI may be enhanced by a heavy metal layer [52,53] on YIG, but consequently the damping will be severely affected [54]. The energy dispersive X-ray spectroscopy and geometric phase analysis [37] are conducted and no significant Gd diffusion [55] is found in the 7 nm-thick YIG film grown by sputtering.…”

supporting

confidence: 74%

Chiral Spin-Wave Velocities Induced by All-Garnet Interfacial Dzyaloshinskii-Moriya Interaction in Ultrathin Yttrium Iron Garnet Films

et al. 2020

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Spin waves can probe the Dzyaloshinskii-Moriya interaction (DMI) which gives rise to topological spin textures, such as skyrmions. However, the DMI has not yet been reported in yttrium iron garnet (YIG) with arguably the lowest damping for spin waves. In this work, we experimentally evidence the interfacial DMI in a 7 nm-thick YIG film by measuring the nonreciprocal spin-wave propagation in terms of frequency, amplitude and most importantly group velocities using all electrical spin-wave spectroscopy. The velocities of propagating spin waves show chirality among three vectors, i.e. the film normal direction, applied field and spin-wave wavevector. By measuring the asymmetric group velocities, we extract a DMI constant of 16 µJ/m 2 which we independently confirm by Brillouin light scattering. Thickness-dependent measurements reveal that the DMI originates from the oxide interface between the YIG and garnet substrate. The interfacial DMI discovered in the ultrathin YIG films is of key importance for functional chiral magnonics as ultra-low spin-wave damping can be achieved. arXiv:1910.02599v2 [cond-mat.mtrl-sci]

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supporting

confidence: 74%

Chiral Spin-Wave Velocities Induced by All-Garnet Interfacial Dzyaloshinskii-Moriya Interaction in Ultrathin Yttrium Iron Garnet Films

et al. 2020

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“…Our predictions can be tested in B20 chiral magnets [1,2], f -electron materials [42,43] and magnetic heterostructures [44][45][46], where multiple-Q spin textures have been observed in experiments. The quantized charge transport can be possibly realized in a heterostructure with the multiple-Q spin texture formed in a magnetic insulator layer or at the interface through the proximity effect [47][48][49]. In materials, the multiple-Q spin textures are pinned by defects.…”

Section: Discussionmentioning

confidence: 99%

Dimension transcendence and anomalous charge transport in magnets with moving multiple- Q spin textures

Hayami

Lin

2020

Phys. Rev. Research

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Multiple-Q spin textures, such as magnetic bubble and skyrmion lattices, have been observed in a large family of magnets. These spin textures can be driven into motion by external stimuli. The motion of spin textures affects the electronic states. Here we show that to describe correctly the electronic dynamics, the momentum space needs to be transcended to higher dimensions by including the ancillary dimensions associated with phason modes of the translational motion of the spin textures. The electronic states have non-trivial topology characterized by the first and second Chern numbers in the high dimensional hybrid momentum space. This gives rise to an anomalous electric charge transport due to the motion of spin textures. By deforming the spin textures, a nonlinear response associated with the second Chern number can be induced and results in the piezoelectricity. The charge transport is derived from the semi-classical equation of motion of electrons that depends on the Berry curvature in the hybrid momentum space. Our results suggest that the motion of multiple-Q spin textures has significant effects on the electronic dynamics and provides a new platform to explore high dimensional topological physics.

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“…Based on both ingredients, chirality and spin-torque, motion of domain wall spin textures with velocities exceeding 800 m/s was recently observed in TmIG [6,7]. The existence of skyrmions has also been suggested recently by electrical signatures [11,12] but remains to be confirmed by direct imaging.…”

Section: Introductionmentioning

confidence: 98%

Thermal nucleation and high-resolution imaging of submicrometer magnetic bubbles in thin thulium iron garnet films with perpendicular anisotropy

Büttner

Mawass

Bauer

et al. 2020

Phys. Rev. Materials

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Ferrimagnetic iron garnets are promising materials for spintronics applications, characterized by ultralow damping and zero current shunting. It has recently been found that few nm-thick garnet films interfaced with a heavy metal can also exhibit sizable interfacial spin-orbit interactions, leading to the emergence, and efficient electrical control, of one-dimensional chiral domain walls. Two-dimensional bubbles, by contrast, have so far only been confirmed in micrometer-thick films. Here, we show by high resolution scanning transmission x-ray microscopy and photoemission electron microscopy that submicrometer bubbles can be nucleated and stabilized in ∼25-nm-thick thulium iron garnet films via short heat pulses generated by electric current in an adjacent Pt strip, or by ultrafast laser illumination. We also find that quasistatic processes do not lead to the formation of a bubble state, suggesting that the thermodynamic path to reaching that state requires transient dynamics. X-ray imaging reveals that the bubbles have Bloch-type walls with random chirality and topology, indicating negligible chiral interactions at the garnet film thickness studied here. The robustness of thermal nucleation and the feasibility demonstrated here to image garnet-based devices by x-rays both in transmission geometry and with sensitivity to the domain wall chirality are critical steps to enabling the study of small spin textures and dynamics in perpendicularly magnetized thin-film garnets.

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Topological Hall effect at above room temperature in heterostructures composed of a magnetic insulator and a heavy metal

Cited by 131 publications

References 41 publications

Chiral Spin-Wave Velocities Induced by All-Garnet Interfacial Dzyaloshinskii-Moriya Interaction in Ultrathin Yttrium Iron Garnet Films

Chiral Spin-Wave Velocities Induced by All-Garnet Interfacial Dzyaloshinskii-Moriya Interaction in Ultrathin Yttrium Iron Garnet Films

Dimension transcendence and anomalous charge transport in magnets with moving multiple- Q spin textures

Thermal nucleation and high-resolution imaging of submicrometer magnetic bubbles in thin thulium iron garnet films with perpendicular anisotropy

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