Berlin 2015 – scientific programme

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MA: Fachverband Magnetismus

MA 4: Micro- and Nanostructured Materials

MA 4.3: Talk

Monday, March 16, 2015, 10:15–10:30, H 1012

The role of vortex-antivortex pairs and cluster knots of domain walls in magnetization reversal — •Sukhvinder Singh, Haibin Gao, and Uwe Hartmann — Institute of Experimental Physics, Saarland University, P O. Box 151150, D66041, Saarbrücken, Germany

Magnetic force microscopy was employed to investigate the role of domain wall substructures in the magnetization reversal in patterned Permalloy thin films in an in-plane magnetic field. This study reveals that the magnetic reversal mechanism proceeds through periodic subdivisions of domain walls connected between cluster knots. The magnetic flux transfer across domain walls was observed to be assisted by nucleation and annihilation of vortex-antivortex pairs in the domain wall. The nucleation of vortex-antivortex pairs creates channels to transfer the magnetic flux across the domain wall. The change in the magnetic energy landscape along the long and short axes was linked to the different evolutions of the domain wall clusters at the edges of the samples. Furthermore, the experimental findings were interpreted and evaluated by comparing and analyzing the results obtained by micromagnetic simulations. By considering the magnetic energies over the whole sweep range of the applied field, it was observed that demagnetization and exchange energies dominate the Zeeman energy only near remnant state. This restricts the transformations of the domain wall substructures to the near zero field range.