Spin-Hall Topological Hall Effect in Highly Tunable Pt/Ferrimagnetic-Insulator Bilayers

Abstract

Electrical detection of topological magnetic textures such as skyrmions is currently limited to conducting materials. While magnetic insulators offer key advantages for skyrmion technologies with high speed and low loss, they have not yet been explored electrically. Here, we report a prominent topological Hall effect in Pt/Tm 3 Fe 5 O 12 bilayers, where the pristine Tm 3 Fe 5 O 12 epitaxial films down to 1.25 unit cell thickness allow for tuning of topological Hall stability over a broad range from 200 to 465 K through atomic-scale thickness control. Although Tm 3 Fe 5 O 12 is insulating, we demonstrate the detection of topological magnetic textures through a novel phenomenon: "spin-Hall topological Hall effect" (SH-THE), where the interfacial spin-orbit torques allow spin-Hall-effect generated spins in Pt to experience the unique topology of the underlying skyrmions in Tm 3 Fe 5 O 12 . This novel electrical detection phenomenon paves a new path for utilizing a large family of magnetic insulators in future skyrmion technologies.

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

“…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.…”

Strain-induced perpendicular magnetic anisotropy and Gilbert damping of Tm3Fe5O12 thin films

“…A similar result was recently found by Ahmed et al . for extremely thin layers (<2 nm) 22 . However, Kubota et al .…”

Probing the Source of the Interfacial Dzyaloshinskii-Moriya Interaction Responsible for the Topological Hall Effect in Metal/Tm3Fe5OLee1, Ahmed2, Flores3 et al. 2020Phys. Rev. Lett.Self Cite463392View full textAdd to dashboardCite

“…Recently, signatures of topological spin textures in Pt/Tm 3 Fe 5 O 12 (TmIG) bilayers have been detected by the topological Hall effect (THE), 11,12 where a spin current is generated in the HM via the spin Hall effect (SHE) and used to detect the FMI magnetization 13,14 and topological spin textures such as skyrmions. However, there are debates in the field on whether the main source of interfacial DMI stems from the HM/FMI interface 11,12 or the FMI/substrate interface, [15][16][17] as well as the mechanism for electrical detection of magnetic textures in HM/FMI bilayers. 11 Recent work on TmIG and Y 3 Fe 5 O 12 films with minimum thicknesses of 5 nm were studied using domain wall and spin wave propagation, which found that either the majority of DMI was generated at the FMI/substrate interface or changing the capping layer did not affect the strength of the DMI.…”

“…11 Recent work on TmIG and Y 3 Fe 5 O 12 films with minimum thicknesses of 5 nm were studied using domain wall and spin wave propagation, which found that either the majority of DMI was generated at the FMI/substrate interface or changing the capping layer did not affect the strength of the DMI. [15][16][17] Previously, 12 we reported the observation of topological Hall effect in Pt/TmIG bilayers within certain temperature (T) regions tunable by the TmIG thickness, which was termed the spin-Hall topological Hall effect (SH-THE). In this letter, we aim to uncover the source of the interfacial DMI and the mechanism for the SH-THE detection of spin textures through a systematic study of TmIG films capped with various metal films and bilayers.…”

“…The TmIG thin films exhibit high crystalline quality with perpendicular magnetic anisotropy and no magnetic dead layer (as an example, 1.85 nm TmIG films remain ferrimagnetically ordered at room temperature). 12 The TmIG films are cooled to room temperature before the deposition of metal layers including Pt, W, Ta, Au, and Ti. Figure 1a shows a cross-sectional scanning transmission electron microscopy (STEM) image of a Pt/TmIG/sGGG(111) sample viewed along the [112 ] direction taken by an aberration corrected FEI Titan 60/300 STEM at 300 kV.…”