Three-dimensional topological magnetic monopoles and their interactions in a ferromagnetic meta-lattice
Year: 2023
Type: article
Abstract: Topological magnetic monopoles, also known as hedgehogs or Bloch points, are three-dimensional (3D) nonlocal spin textures that are robust to thermal and quantum fluctuations due to their topology1-4. Understanding their properties is of both fundamental interest and practical applications1-9. However, it has been difficult to experimentally produce topological magnetic monopoles in a controlled manner and directly observe their 3D magnetization vector field and interactions at the nanoscale. Here, we report the creation of 138 stable topological magnetic monopoles at the specific sites of a ferromagnetic meta-lattice at room temperature. We further develop 3D soft x-ray vector ptychography to determine the magnetization vector and emergent magnetic field of the topological monopoles with a 3D spatial resolution of 10 nm. This spatial resolution is comparable to the magnetic exchange length of transition metals10, enabling us to probe monopole-monopole interactions. We find that the topological monopole pairs with positive and negative charges are separated by 18.3±1.6 nm, while the positively and negatively charged pairs are stabilized at comparatively longer distances of 36.1±2.4 nm and 43.1±2.0 nm, respectively. We also observe virtual topological monopoles created by magnetic voids in the meta-lattice. This work demonstrates that ferromagnetic meta-lattices could be used as a new platform to create and investigate the interactions and dynamics of topological magnetic monopoles. Furthermore, we expect that soft x-ray vector ptychography can be broadly applied to quantitatively image 3D vector fields in magnetic and anisotropic materials at the nanoscale.
Source: Nature Nanotechnology
Authors: Arjun Rana, Chen-Ting Liao, Ezio Iacocca, Ji Zou, Minh Pham, Xingyuan Lu, Emma-Elizabeth Cating Subramanian, Yuan Hung Lo, Sinéad A. Ryan, Charles S. Bevis, Robert M. Karl, Andrew J. Glaid, Jeffrey Rable, Pratibha Mahale, Joel Hirst, Thomas Ostler, William Liu, Colum M. O’Leary, Young-Sang Yu, Karen Bustillo, Hendrik Ohldag, David A. Shapiro, Sadegh Yazdi, Thomas E. Mallouk, Stanley J. Osher, Henry C. Kapteyn, Vincent H. Crespi, John V. Badding, Yaroslav Tserkovnyak, Margaret M. Murnane, Jianwei Miao
Institutions: California NanoSystems Institute, University of California, Los Angeles, University of Colorado Boulder, Joint Institute for Laboratory Astrophysics, Northumbria University, University of Colorado Colorado Springs, Soochow University, Pennsylvania State University, University of Pennsylvania, Sheffield Hallam University, University of Hull, Lawrence Berkeley National Laboratory, Advanced Light Source, Molecular Foundry
Language: English
Subfield: Atomic and Molecular Physics, and Optics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
Funders: National Science Foundation, U.S. Department of Energy, Defense Advanced Research Projects Agency, Office of Science, Multidisciplinary University Research Initiative, Division of Materials Research, Basic Energy Sciences, Army Research Office, Division of Materials Sciences and Engineering
Awards: G1286236842, G1286251239, G1314494723, G1395360581, G1863003419, NONEQUILIBRIUM THERMODYNAMICS IN MAGNETIC NANOSTRUCTURES, G237429762, G2618837358, G2810384502, G2999910790, G30714459, G3083819904, G3128650482, G419881185, G42916606, G4481661474, G4501827968, G498139845, G5080714059, G5206177008, G5222170445, G5255510351, NEW; SISGR: ULTRAFAST MAGNETISM DYNAMICS MESAURE USING TABLETOP ULTRAFAST EUV SOURCES; PI- MARGARET MURNANE, NEW; SISGR: ULTRAFAST MAGNETISM DYNAMICS MESAURE USING TABLETOP ULTRAFAST EUV SOURCES; PI- MARGARET MURNANE, G650090426, G6652958823, G7452299184, THREE-DIMENSIONAL CHARACTERIZATION OF NANOMATERIALS AT ATOMIC RESOLUTION USING STEM TOMOGRAPHY, G791371132, Science and Technology Center on Real-Time Functional Imaging (STROBE), G8825387107, G8905037300, G969889393
OpenAlex ID: W4317757487