Imaging magnetic vortex configurations in ferromagnetic nanotubes

M. Wyss,1 A. Mehlin,1 B. Gross,1 A. Buchter,1 A. Farhan,2,3 M. Buzzi,4 A. Kleibert,4 G. Tütüncüoglu,5 F. Heimbach,6 A. Fontcuberta i Morral,5 D. Grundler,7 and M. Poggio1,* 1Department of Physics, University of Basel, 4056 Basel, Switzerland 2Laboratory for Microand Nanotechnology, Paul Scherrer Institute, 5232 Villigen, Switzerland 3Laboratory for Mesoscopic Systems, Department of Materials, ETH Zürich, 8093 Zürich, Switzerland 4Swiss Light Source, Paul Scherrer Institute, 5232 Villigen, Switzerland 5Laboratory of Semiconductor Materials, Institute of Materials (IMX), School of Engineering, École Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland 6Lehrstuhl für Physik funktionaler Schichtsysteme, Physik Department E10, Technische Universität München, 85747 Garching, Germany 7Laboratory of Nanoscale Magnetic Materials and Magnonics, Institute of Materials (IMX), School of Engineering, École Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland (Received 21 February 2017; published 17 July 2017)