Tailoring magnetic energies to form dipole skyrmions and skyrmion lattices

Authors :: Montoya, S. A.
Couture, S.
Chess, J. J.
Lee, J. C. T.
Kent, N.
Henze, D.
Sinha, S. K.
Im, M. -Y.
Kevan, S. D.
Fischer, P.
McMorran, B. J.
Lomakin, V.
Roy, S.
Fullerton, E. E.
Source :: Phys. Rev. B 95, 024415 (2017)
Publication Year :: 2016
Abstract: The interesting physics and potential memory technologies resulting from topologically protected spin textures such as skyrmions, has prompted efforts to discover new material systems that can host these kind of magnetic structures. Here we use the highly tunable magnetic properties of amorphous Fe/Gd multilayer films to explore the magnetic properties that lead to dipole-stabilized skyrmions and skyrmion lattices that form from the competition of dipolar field and exchange energy. Using both real space imaging and reciprocal space scattering techniques we determined the range of material properties and magnetic fields where skyrmions form. Micromagnetic modeling closely matches our observation of small skyrmion features (~50 to 70nm) and suggests these class of skyrmions have a rich domain structure that is Bloch like in the center of the film and more N\'eel like towards each surface. Our results provide a pathway to engineer the formation and controllability of dipole skyrmion phases in a thin film geometry at different temperatures and magnetic fields.<br />Comment: 34 pages, 11 figures