| Skyrmion crystals are regular arrangements of magnetic whirls that exist in a wide range of chiral magnets. Due to their topology, they cannot be created or destroyed by smooth rearrangements of the direction of the local magnetization. Using magnetic force microscopy we tracked the destruction of the skyrmion lattice on the surface of a bulk crystal of Fe(1-x)Co(x)Si (x = 0.5). Our study reveals that skyrmions vanish by a coalescence forming elongated structures. The observed microscopic changes of the magnetic texture at the sample surface are related to the sample volume via small angle neutron scattering experiments. Numerical simulations show that changes of topology are controlled by singular magnetic point defects. They can be viewed as quantized magnetic monopoles and antimonopoles, which provide sources and sinks of one flux quantum of emergent magnetic flux, respectively. |
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