| Autor: |
Je SG; Center for X-ray Optics, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States.; Department of Emerging Materials Science, DGIST, Daegu 42988, Korea.; Center for Spin-Orbitronic Materials, Korea University, Seoul 02841, Korea.; Department of Physics, Chonnam National University, Gwangju 61186, Korea., Han HS; School of Materials Science and Engineering, Ulsan National Institute of Science and Technology, Ulsan 44919, Korea., Kim SK; Department of Physics and Astronomy, University of Missouri, Columbia, Missouri 65211, United States., Montoya SA; Space and Naval Warfare Systems Center Pacific, San Diego, California 92152, United States., Chao W; Center for X-ray Optics, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States., Hong IS; KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul 02841, Korea., Fullerton EE; Center for Memory and Recording Research, University of California-San Diego, La Jolla, California 92093, United States.; Department of Electrical and Computer Engineering, University of California-San Diego, La Jolla, California 92093, United States., Lee KS; School of Materials Science and Engineering, Ulsan National Institute of Science and Technology, Ulsan 44919, Korea., Lee KJ; KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul 02841, Korea.; Department of Materials Science and Engineering, Korea University, Seoul 02841, Korea., Im MY; Center for X-ray Optics, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States.; Department of Emerging Materials Science, DGIST, Daegu 42988, Korea.; School of Materials Science and Engineering, Ulsan National Institute of Science and Technology, Ulsan 44919, Korea., Hong JI; Department of Emerging Materials Science, DGIST, Daegu 42988, Korea. |
| Abstrakt: |
Topological protection precludes a continuous deformation between topologically inequivalent configurations in a continuum. Motivated by this concept, magnetic skyrmions, topologically nontrivial spin textures, are expected to exhibit topological stability, thereby offering a prospect as a nanometer-scale nonvolatile information carrier. In real materials, however, atomic spins are configured as not continuous but discrete distributions, which raises a fundamental question if the topological stability is indeed preserved for real magnetic skyrmions. Answering this question necessitates a direct comparison between topologically nontrivial and trivial spin textures, but the direct comparison in one sample under the same magnetic fields has been challenging. Here we report how to selectively achieve either a skyrmion state or a topologically trivial bubble state in a single specimen and thereby experimentally show how robust the skyrmion structure is in comparison with the bubbles. We demonstrate that topologically nontrivial magnetic skyrmions show longer lifetimes than trivial bubble structures, evidencing the topological stability in a real discrete system. Our work corroborates the physical importance of the topology in the magnetic materials, which has hitherto been suggested by mathematical arguments, providing an important step toward ever-dense and more-stable magnetic devices. |
