Visualizing Magnetic Structure in 3D Nanoscale Ni–Fe Gyroid Networks

• DOI: 10.1021/acs.nanolett.0c00578
• Publication Date: 2020-04-06T18:05:51Z
• Authors: Justin Llandro; David M. Love; András Kovács; Jan Caron; Kunal N. Vyas; Attila Kákay; Ruslan Salikhov; Kilian Lenz; Jürgen Fassbender; Maik R. J. Scherer; Christian Cimorra; Ullrich Steiner; Crispin H. W. Barnes; Rafal E. Dunin-Bo...; Shunsuke Fukami; Hideo Ohno
• Keywords: Gyroid

Arrays of interacting 2D nanomagnets display unprecedented electromagnetic properties via collective effects, demonstrated in artificial spin ices and magnonic crystals. Progress toward 3D magnetic metamaterials is hampered by two challenges: fabricating structures near intrinsic length scales (sub-100 nm) visualizing their configurations. Here, we fabricate measure nanoscale gyroids, periodic chiral networks comprising nanowire-like struts forming three-connected vertices. Via block copolymer templating, produce Ni75Fe25 single-gyroid double-gyroid (an inversion pair single-gyroids) nanostructures with a 42 nm unit cell 11 diameter struts, comparable to the exchange Ni-Fe. We visualize magnetization distributions off-axis electron holography nanometer spatial resolution interpret patterns using finite-element micromagnetic simulations. Our results suggest an intricate, frustrated remanent state which ferromagnetic but without unique equilibrium configuration, opening new possibilities for phenomena magnetism, including crystals unconventional computing.