Berlin 2012 – scientific programme
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MA: Fachverband Magnetismus
MA 47: Micro- and Nanostructured Magnetic Materials II
MA 47.1: Talk
Thursday, March 29, 2012, 17:15–17:30, EB 202
Magnetism on Curved Surfaces — •Robert Streubel1,2, Denys Makarov1, Florian Kronast3, and Oliver G. Schmidt1,2 — 1Institute for Integrative Nanosciences, IFW Dresden, 01069 Dresden, Germany — 2Material Systems for Nanoelectronics, Chemnitz University of Technology, 09107 Chemnitz, Germany — 3Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, 12489 Berlin, Germany
An elegant way to alter the fundamental magnetic interactions at the nanoscale is to introduce a curvature that leads to local thickness variation. In this respect, we investigated magnetic properties in permalloy (Py, Ni80Fe20) caps on both SiO2 spherical particles with diameters from 100 to 800 nm and tubular non-magnetic rolled-up tubes with diameters from 250 to 1,700 nm. Both equilibrium and remanent states of individual caps and close-packed cap arrays were visualized by means of X-ray magnetic circular dichroism photoemission electron microscopy (XMCD-PEEM). The weak magnetostatic coupling leads to a chirality coupling with specific space-filling patterns. Vortex nucleation and annihilation fields of cap arrays are 5 times smaller than of equivalent individual planar disks and more than 3 times larger than of close-packed arrays of planar disks. Both temperature-dependent hysteresis measurements and relaxation measurements were performed to estimate the energy barrier for vortex nucleation and annihilation.