Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

We report on pairs of converging-diverging spin vortices in Co/Rh/NiFe trilayer disks. The lateral magnetization distribution of these effective spin merons is directly imaged by means of element-selective x-ray microscopy. By this method, both the divergence and circulation states of the individual layers are identified to be antisymmetric. Reversal measurements on corresponding continuous films reveal that biquadratic interlayer exchange coupling is the cause for the formation of the effective meron pairs observed. Furthermore their three-dimensional magnetization structure is determined by micromagnetic simulations. It is shown that in order to reduce magnetic surface and volume charges the magnetic induction aligns along a flux-closing torus. This toroidal topology enforces a symmetry break, which links the core polarities to the divergence configuration.