A Van der Waals Interface Hosting Two Groups of Magnetic Skyrmions

TLDR

Multiple magnetic skyrmion phases provide an extra degree of freedom for ultrahigh‑density spin memory, and extending the field to 2D van der Waals magnets adds further tunability via thickness, twist angle, and gating, enabling high skyrmion density and enhanced functionality. The study reports a van der Waals interface between Cr₂Ge₂Te₆ and Fe₃GeTe₂ that hosts two distinct groups of magnetic skyrmions. The interface is fabricated from Cr₂Ge₂Te₆ and Fe₃GeTe₂ layers, and the skyrmion groups are imaged by magnetic force microscopy and corroborated by micromagnetic simulations. Two distinct topological Hall effect signals appear below 60 K, the skyrmions persist without an applied field, and these results suggest van der Waals heterostructures with multiple skyrmion phases could enable skyrmionic devices.

Abstract

Multiple magnetic skyrmion phases add an additional degree of freedom for skyrmion-based ultrahigh-density spin memory devices. Extending the field to 2D van der Waals magnets is a rewarding challenge, where the realizable degree of freedoms (e.g., thickness, twist angle, and electrical gating) and high skyrmion density result in intriguing new properties and enhanced functionality. In this work, a van der Waals interface, formed by two 2D ferromagnets Cr2 Ge2 Te6 and Fe3 GeTe2 with a Curie temperature of ≈65 and ≈205 K, respectively, hosting two groups of magnetic skyrmions, is reported. Two sets of topological Hall effect signals are observed below 6s0 K when Cr2 Ge2 Te6 is magnetically ordered. These two groups of skyrmions are directly imaged using magnetic force microscopy, and supported by micromagnetic simulations. Interestingly, the magnetic skyrmions persist in the heterostructure with zero applied magnetic field. The results are promising for the realization of skyrmionic devices based on van der Waals heterostructures hosting multiple skyrmion phases.