A Library of Dipolar Skyrmion Bags Observed in a Centrosymmetric van der Waals Magnet

Abstract

ABSTRACT Topological magnetic solitons, such as skyrmions, exhibit topological protection and emergent electrodynamics that make them compelling for both fundamental research and spintronic applications. Beyond the canonical skyrmion, higher‐order and composite textures, such as skyrmion bag, offer arbitrary topological charges and internal morphology that critically governs their energetics and excitation dynamics. However, despite numerous theoretical proposals, experimental access to distinct skyrmion‐bag morphologies has so far been scarce and mainly confined to Dzyaloshinskii‐Moriya‐interaction (DMI)‐based systems. Here, we demonstrate a broad spectrum of skyrmion bags by using femtosecond‐laser excitation in a centrosymmetric van der Waals magnet Cr 1.6 Ti 0.03 Te 2 , referred to as dipolar skyrmion bags. The observed skyrmion bags are composed of closed domain‐wall loops with different circularities and varying loop numbers, as well as their corresponding type‐II counterparts, far beyond the limited skyrmion bags in DMI systems. Combining Lorentz transmission electron microscopy with micromagnetic simulations, we investigate in details their stability, circularity‐dependent field evolution, and distinct annihilation channels. This work substantially expands the experimentally accessible family of topological spin textures and pave the way toward multi‐state, reconfigurable spintronic functionalities based on dipolar skyrmion bags.