Fig. 1: Nucleation of merons and antimerons during the cooling process.
From: Properties and dynamics of meron topological spin textures in the two-dimensional magnet CrCl3
a–c Dynamical spin configurations obtained at different temperatures (T) showing the evolution of the domain structure and the formation of merons and antimerons during field cooling in an external field of 0.0 mT. The Sz component is used to follow the evolution of the different spin textures across the crystal surface (color map). Strong spin fluctuations are observed at temperatures below the critical temperature (Tc = 19.07 K, see Supplementary Fig S1), which incidentally vanished as the system cools down. Localized small areas within 0 K ≤ T ≤ 5 K correspond to spins pointed perpendicular to the easy-plane of CrCl3 in different spin polarizations (e.g., +1 or −1). At 0 K, most of the magnitudes of Sz are zero throughout the crystal except at well defined small spots with either Sz = +1 or Sz = −1 in their cores. The formation of merons and antimerons occur simultaneously during the time evolution without a clear preference over the nucleation site. That is, boundaries, defects or edges are not considered. d–f Similar to a–c but at an external field of 50 mT. The applied field polarizes the spin configurations resulting in less fluctuations along of Sz even though with alike domain dynamics. At T ≤ 5 K, the merons and antimerons are still formed but with a more preferential spin polarization, e.g., darker spots. If larger magnetic fields beyond 50 mT are applied (e.g., 100 mT), a full polarization of the topological spin textures is observed with a totality of just one kind of spin polarization. For fields above 150 mT, there is no additional nucleation of merons and antimerons throughout the crystal as the spin textures outside the vortex core follows the field direction. See Supplementary Figs. S2, S3 and Supplementary Movies S1–S3 for details. Scale bar is 50 nm.
