Symmetry breaking of magnetic vortices before annihilation
Magnetic vortices in nanoscopic ferromagnetic elements can be treated as solitons that exhibit static and dynamic stability even above room temperature, making them promising for technological applications. Although their properties at low energy configurations have been well studied, the properties of solitons undergoing structural breakdown are poorly understood. Here, we destabilize the soliton through Zeeman and demagnetization interactions and investigate the symmetry breaking of the magnetic vortex state. Using high-resolution Lorentz imaging and numerical simulations, we observe phase transitions of the core from the characteristic point-like structure into distinct extended asymmetric states differentiated by the polarity. The deformations start at intermediate displacements and are traced until the point of annihilation at the disc's edge. We discuss the use of these asymmetric states as a method to determine the core polarity for in-plane magnetic imaging techniques.
Applied Physics Letters
Pulecio, J., Pollard, S., Warnicke, P., Arena, D., & Zhu, Y. (2014). Symmetry breaking of magnetic vortices before annihilation. Applied Physics Letters, 105 (13) https://doi.org/10.1063/1.4893422