Spontaneous (Anti)meron Chains in the Domain Walls of van der Waals Ferromagnetic Fe5- x GeTe2.

The promise of topologically vortex-like magnetic spin textures hinges on the intriguing physical properties and theories in fundamental research and their distinguished roles as high-efficiency information units in future spintronics. The exploration of such magnetic states with unique spin configurations has never ceased. In this study, the emergence of unconventional (anti)meron chains from a domain wall pair is directly observed at zero field in 2D ferromagnetic Fe5- x GeTe2 , closely correlated with significant enhancement of the in-plane magnetization and weak van der Waals interactions. The simultaneous appearance of a large topological Hall effect is observed at the same temperature range as that of the abnormal magnetic transition. Moreover, the distinctive features of the (anti)meron chains and their collective dynamic behavior under external fields may provide concrete experimental evidence for the recent theoretical prediction of the magnetic-domain-wall topology and endorse a broader range of possibilities for electronics, spintronics, condensed matter physics, etc.