Creation of skyrmions in van der Waals ferromagnet Fe ₃ GeTe ₂ on (Co/Pd) _n superlattice

Abstract

Magnetic skyrmions are topological spin textures, which usually exist in noncentrosymmetric materials where the crystal inversion symmetry breaking generates the so-called Dzyaloshinskii-Moriya interaction. This requirement unfortunately excludes many important magnetic material classes, including the recently found two-dimensional van der Waals (vdW) magnetic materials, which offer unprecedented opportunities for spintronic technology. Using photoemission electron microscopy and Lorentz transmission electron microscopy, we investigated and stabilized Néel-type magnetic skyrmion in vdW ferromagnetic Fe3GeTe2 on top of (Co/Pd)n in which the Fe3GeTe2 has a centrosymmetric crystal structure. We demonstrate that the magnetic coupling between the Fe3GeTe2 and the (Co/Pd)n could create skyrmions in Fe3GeTe2 without the need of an external magnetic field. Our results open exciting opportunities in spintronic research and the engineering of topologically protected nanoscale features by expanding the group of skyrmion host materials to include these previously unknown vdW magnets.

Néel-type skyrmions and their current-induced motion in van der Waals ferromagnet-based heterostructures

“…Once established, by taking advantages of other 2D crystals that are stackable and offer unique electrical properties [1,2], this material platform could provide a different route towards skyrmion-based devices that have been challenging with conventional metallic ferromagnets [20,21]. Recently, skyrmionlike spin textures have been observed experimentally in exfoliated vdW ferromagnet materials (e.g., FGT and Cr 2 Ge 2 Te 6 ) and their heterostructures with the magnetic fields [22][23][24][25][26]. However, both Bloch-type and Néel-type skyrmions of the previous results have still been a subject of controversy.…”

Phase Selection in Mn–Si Alloys by Fast Solid‐State Reaction with Enhanced Skyrmion Stability

“…The size of skyrmions or the associated magnetic modulation period is determined by the ratio between the magnitudes of the DM interaction and the ferromagnetic exchange interaction, and typically ranges from 1 to 100 nm. [ 4–8 ] To drive skyrmions, a much smaller current is needed in comparison to those used to generate spin transfer torques in ferromagnetic metals, which results in lower power consumption and decreases the Joule heat. [ 9–11 ] Magnetic skyrmions are proposed for applications in new‐generation data storage.…”

Unconventional Hall effect and its variation with Co-doping in van der Waals Fe3GeTe2

“…On the other hand, the possibility of utilization of centrosymmetric FMs as topological spin texture hosting materials was completely neglected owing to symmetry requirements, which dictates the absence of DMI in these systems. Recent experimental results have demonstrated the formation of topological skyrmion lattice and/or chiral structures in single-crystalline bulk FGT 15 , 43 , exfoliated nanoflakes 16 , 44 , and formation of Néel-type skyrmions in FGT-based heterostructures 44 – 46 . However, the experimental results from the magnetoresistive measurements 9 , 17 , 18 cannot be solely interpreted to arise from submicron skyrmion bubble-like textures, demonstrated by magnetic imaging techniques 15 .…”