Magneto-Optical Imaging of Vortex Domain Deformation in Pinning Sites

Abstract

We use a sensitive magneto-optical microscopy technique to image the magnetization response of micron-scale ferromagnetic disks to changes in applied magnetic field. This differential technique relies on a modulated applied magnetic field which allows us to measure changes in magnetization <1% with sub-micron resolution. The disks are magnetized in single vortex domains, with defects in the material serving to pin the vortex core at particular positions. By applying a small AC magnetic field, we measure the deformation of the magnetization while the core remains pinned. We can also characterize the strength of the pinning site by increasing the AC magnetic field to unpin the vortex core. While pinned, we find that the magnetization away from the core reorients slightly to better align with an applied field. Additionally, an applied field causes the pinned core itself to tilt in the direction of the field. Once the field is large enough to unpin the core, this tilt disappears, and the core instead translates across the disk.

6 pages, 4 figures

References in corpus (6)

• Magnetic Vortex Resonance in Patterned Ferromagnetic Dots
• Dynamics of Pinned Magnetic Vortices
• Effects of Disorder and Internal Dynamics on Vortex Wall Propagation
• Magnetic memory and current amplification devices using moving domain walls
• How hole defects modify vortex dynamics in ferromagnetic nanodisks
• The effect of disorder on transverse domain wall dynamics in magnetic nanostrips

Cited by in corpus (5)

• Fast, nanoscale addressability of nitrogen-vacancy spins via coupling to a dynamic ferromagnetic vortex
• Nanowire magnetic force sensors fabricated by focused electron beam induced deposition
• Mapping the domain wall pinning landscape in ferromagnetic films
• Relaxation of a single defect spin by the low-frequency gyrotropic mode of a magnetic vortex
• Broadband optomechanical transduction of nanomagnetic spin modes