Ordering of room-temperature magnetic skyrmions in a polar van der Waals magnet

Abstract

Control and understanding of ensembles of skyrmions is important for realization of future technologies. In particular, the order-disorder transition associated with the 2D lattice of magnetic skyrmions can have significant implications for transport and other dynamic functionalities. To date, skyrmion ensembles have been primarily studied in bulk crystals, or as isolated skyrmions in thin film devices. Here, we investigate the condensation of the skyrmion phase at room temperature and zero field in a polar, van der Waals magnet. We demonstrate that we can engineer an ordered skyrmion crystal through structural confinement on the μm scale, showing control over this order-disorder transition on scales relevant for device applications.

Room-temperature sub-100 nm Néel-type skyrmions in non-stoichiometric van der Waals ferromagnet Fe3-xGaTe2 with ultrafast laser writability

“…Although several methods, such as elemental doping and substitution etc. 29 , 30 , have shown the possibility to increase T c while breaking the centrosymmetric structure for creating DMI in intrinsic 2D vdW ferromagnets 31 , 32 , the elemental controllability and raising the T c above RT are still challenging 33 , 34 . One better choice is to directly introduce DMI into intrinsic 2D vdW ferromagnets with T c above RT.…”

Spin disorder control of topological spin texture

“…3d , and the bond orientational parameter ( ) is close to 1 in Fig. 3e , indicating a solid-phase skyrmion lattice 40 . In contrast, the presence of numerous 5-7 pairs caused by the stripe dislocations and the parameter significantly below 1 suggests a liquid-phase skyrmion lattice in the Ferro-phase regions.…”

“…(Supplementary Fig. 18 ) A triangle-ordered Néel-type skyrmion lattice can be stabilized in the Fe 2.5 Co 2.5 GeTe 2 nanoflake 40 . Interestingly, a distinct contrast of the skyrmion lattices in the Fe 3 GaTe 2 nanoflakes with 8.5% Fe int is present (Fig.…”

“…3a. Statistical analysis was conducted following the same methodology as in the previous reference 40 . f The MFM image of a Fe 3 GaTe 2 with 65.3% Fe int nanoflake at room temperature and zero field shows a disordered skyrmion lattice.…”

Above-room-temperature chiral skyrmion lattice and Dzyaloshinskii–Moriya interaction in a van der Waals ferromagnet Fe3−xGaTe2

“…For instance, though Néel skyrmions are observed in self-intercalated chromium telluride 34 , more studies report Bloch-type achiral skyrmions and biskyrmions even with similar intercalate concentrations 28 , 29 , 37 , implying that the asymmetric intercalation is challenging. (Fe 0.5 Co 0.5 ) 5 GeTe 2 is a remarkable material that can host Néel skyrmion lattice up to 312 K at zero magnetic field 17 , 38 . To obtain the high-temperature ferromagnetic order, the key factors are precisely regulating the Co-doping concentration at ~50% and acquiring the AA ’-type layer stacking 39 , 40 .…”