Coexistence of Merons with Skyrmions in the Centrosymmetric Van Der Waals Ferromagnet Fe5–xGeTe2

Fe5–xGeTe2 is a centrosymmetric, layered van der Waals (vdW) ferromagnet that displays Curie temperatures Tc (270–330 K) that are within the useful range for spintronic applications. However, little is known about the interplay between its topological spin textures (e.g., merons, skyrmions) with technologically relevant transport properties such as the topological Hall effect (THE) or topological thermal transport. Here, via high‐resolution Lorentz transmission electron microscopy, it is shown that merons and anti‐meron pairs coexist with Néel skyrmions in Fe5–xGeTe2 over a wide range of temperatures and probe their effects on thermal and electrical transport. A THE is detected, even at room T, that senses merons at higher T's, as well as their coexistence with skyrmions as T is lowered, indicating an on‐demand thermally driven formation of either type of spin texture. Remarkably, an unconventional THE is also observed in absence of Lorentz force, and it is attributed to the interaction between charge carriers and magnetic field‐induced chiral spin textures. These results expose Fe5–xGeTe2 as a promising candidate for the development of applications in skyrmionics/meronics due to the interplay between distinct but coexisting topological magnetic textures and unconventional transport of charge/heat carriers. B. W. Casas, Y. Li, A. Moon, Y. Xin, C. McKeever, J. Macy, A. K. Petford‐Long, C. M. Phatak, E. J. G. Santos, E. S. Choi, L. Balicas Contour plot displays the magnitude of the conventional topological Hall effect (THE), revealing that it is particularly strong up to room temperature. Inset: Lorentz‐TEM image from an area of the sample collected at T = 100 K, highlighting the coexistence of magnetic domains having in‐plane oriented spins that yield merons (green shaded regions) with out‐of‐plane ones (purple shaded regions) where skyrmions are observed under a magnetic field.