Regensburg 2019 – scientific programme
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MA: Fachverband Magnetismus
MA 43: Micro- and nanostructured magnetic materials
MA 43.6: Talk
Thursday, April 4, 2019, 10:45–11:00, H52
Origin and Manipulation of Stable Vortex Ground States in Permalloy Nanotubes — Michael Zimmermann1, •Thomas Meier1, Florian Dirnberger1, Attila Kákay2, Martin Decker1, Sebastian Wintz2,3, Simone Finizio3, Elisabeth Josten2, Jörg Raabe3, Matthias Kronseder1, Dominique Bougeard1, Jürgen Lindner2, and Christian Back4,1 — 1Institut für experimentelle und angewandte Physik, Universität Regensburg — 2Helmholtz-Zentrum, Dresden Rossendorf, Institute of Ion Beam Physics and Material Science — 3Paul Scherrer Institut, Villigen, Schweiz — 4Physik-Department, Technische Universität München
We present a detailed study on the static magnetic properties of individual permalloy nanotubes (NTs) with hexagonal cross-sections. Anisotropic magnetoresistance (AMR) measurements and scanning transmission X-ray microscopy (STXM) are used to investigate their magnetic ground states and its stability. We find that the magnetization in zero applied magnetic field is in a very stable vortex state. Its origin is attributed to a strong growth-induced anisotropy with easy axis perpendicular to the long axis of the tubes. AMR measurements of individual NTs in combination with micromagnetic simulations allow the determination of the magnitude of the growth-induced anisotropy for different types of NT coatings. We show that the strength of the anisotropy can be controlled by introducing a buffer layer underneath the magnetic layer. The magnetic ground states depend on the external magnetic field history and are directly imaged using STXM.