Abstract

A Bloch point (BP) is a topological defect in a ferromagnet at which the local magnetization vanishes. With the difficulty of generating a stable BP in magnetic nanostructures, the intrinsic nature of a BP and its dynamic behaviour has not been verified experimentally. We report a realization of steady-state BPs embedded in deformed magnetic vortex cores in asymmetrically shaped Ni80Fe20 nanodisks. Time-resolved nanoscale magnetic X-ray imaging combined with micromagnetic simulation shows detailed dynamic character of BPs, revealing rigid and limited lateral movements under magnetic field pulses as well as its crucial role in vortex-core dynamics. Direct visualizations of magnetic structures disclose the unique dynamical feature of a BP as an atomic scale discrete spin texture and allude its influence on the neighbouring spin structures such as magnetic vortices.

The intrinsic nature and dynamics of a Bloch point has not been verified so far. Here, Im et al. report the realization and dynamical character of steady-state Bloch points in the magnetic vortex cores in asymmetrically shaped Ni80Fe20 nanodisks.

Details

Title
Dynamics of the Bloch point in an asymmetric permalloy disk
Author
Mi-Young, Im 1 ; Hee-Sung, Han 2 ; Min-Seung, Jung 3 ; Young-Sang, Yu 4 ; Lee, Sooseok 2 ; Yoon Seongsoo 3 ; Chao Weilun 5 ; Fischer, Peter 6   VIAFID ORCID Logo  ; Jung-Il, Hong 3 ; Ki-Suk, Lee 2   VIAFID ORCID Logo 

1  Lawrence Berkeley National Laboratory, Center for X-ray Optics, Berkeley, USA (GRID:grid.184769.5) (ISNI:0000 0001 2231 4551); DGIST, Department of Emerging Materials Science, Daegu, Republic of Korea (GRID:grid.417736.0) (ISNI:0000 0004 0438 6721); Ulsan National Institute of Science and Technology, School of Materials Science and Engineering, Ulsan, Republic of Korea (GRID:grid.42687.3f) (ISNI:0000 0004 0381 814X) 
2  Ulsan National Institute of Science and Technology, School of Materials Science and Engineering, Ulsan, Republic of Korea (GRID:grid.42687.3f) (ISNI:0000 0004 0381 814X) 
3  DGIST, Department of Emerging Materials Science, Daegu, Republic of Korea (GRID:grid.417736.0) (ISNI:0000 0004 0438 6721) 
4  Lawrence Berkeley National Laboratory, Advanced Light Source, Berkeley, USA (GRID:grid.184769.5) (ISNI:0000 0001 2231 4551) 
5  Lawrence Berkeley National Laboratory, Center for X-ray Optics, Berkeley, USA (GRID:grid.184769.5) (ISNI:0000 0001 2231 4551) 
6  Lawrence Berkeley National Laboratory, Materials Sciences Division, Berkeley, USA (GRID:grid.184769.5) (ISNI:0000 0001 2231 4551); University of California, Santa Cruz, Department of Physics, Santa Cruz, USA (GRID:grid.205975.c) (ISNI:0000 0001 0740 6917) 
Publication year
2019
Publication date
Feb 2019
Publisher
Nature Publishing Group
e-ISSN
20411723
Source type
Scholarly Journal
Language of publication
English
DOI
https://doi.org/10.1038/s41467-019-08327-6
ProQuest document ID
2176250633
Copyright
This work is published under http://creativecommons.org/licenses/by/4.0/ (the “License”). Notwithstanding the ProQuest Terms and Conditions, you may use this content in accordance with the terms of the License.