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Dao C, Everts JC, Ravnik M, Tserkovnyak Y. Nematronics: Reciprocal Coupling between Ionic Currents and Nematic Dynamics. PHYSICAL REVIEW LETTERS 2023; 130:168102. [PMID: 37154639 DOI: 10.1103/physrevlett.130.168102] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2022] [Accepted: 03/31/2023] [Indexed: 05/10/2023]
Abstract
Adopting a spintronics-inspired approach, we study the reciprocal coupling between ionic charge currents and nematic texture dynamics in a uniaxial nematic electrolyte. Assuming quenched fluid dynamics, we develop equations of motion analogously to spin torque and spin pumping. Based on the principle of least dissipation of energy, we derive the adiabatic "nematic torque" exerted by ionic currents on the nematic director field as well as the reciprocal motive force on ions due to the orientational dynamics of the director. We discuss several simple examples that illustrate the potential functionality of this coupling. Furthermore, using our phenomenological framework, we propose a practical means to extract the coupling strength through impedance measurements on a nematic cell. Exploring further applications based on this physics could foster the development of nematronics-nematic iontronics.
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Affiliation(s)
- Chau Dao
- Department of Physics and Astronomy and Bhaumik Institute for Theoretical Physics, University of California, Los Angeles, Los Angeles, California 90095, USA
| | - Jeffrey C Everts
- Institute of Physical Chemistry, Polish Academy of Sciences, 01-224 Warsaw, Poland
- Institute of Theoretical Physics, Faculty of Physics, University of Warsaw, Pasteura 5, 02-093 Warsaw, Poland
| | - Miha Ravnik
- Faculty of Mathematics and Physics, University of Ljubljana, Jadranska 19, 1000 Ljubljana, Slovenia
- Department of Condensed Matter Physics, Jozef Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia
| | - Yaroslav Tserkovnyak
- Department of Physics and Astronomy and Bhaumik Institute for Theoretical Physics, University of California, Los Angeles, Los Angeles, California 90095, USA
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Rana A, Liao CT, Iacocca E, Zou J, Pham M, Lu X, Subramanian EEC, Lo YH, Ryan SA, Bevis CS, Karl RM, Glaid AJ, Rable J, Mahale P, Hirst J, Ostler T, Liu W, O'Leary CM, Yu YS, Bustillo K, Ohldag H, Shapiro DA, Yazdi S, Mallouk TE, Osher SJ, Kapteyn HC, Crespi VH, Badding JV, Tserkovnyak Y, Murnane MM, Miao J. Three-dimensional topological magnetic monopoles and their interactions in a ferromagnetic meta-lattice. NATURE NANOTECHNOLOGY 2023; 18:227-232. [PMID: 36690739 DOI: 10.1038/s41565-022-01311-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Accepted: 12/13/2022] [Indexed: 05/21/2023]
Abstract
Topological magnetic monopoles (TMMs), also known as hedgehogs or Bloch points, are three-dimensional (3D) non-local spin textures that are robust to thermal and quantum fluctuations due to the topology protection1-4. Although TMMs have been observed in skyrmion lattices1,5, spinor Bose-Einstein condensates6,7, chiral magnets8, vortex rings2,9 and vortex cores10, it has been difficult to directly measure the 3D magnetization vector field of TMMs and probe their interactions at the nanoscale. Here we report the creation of 138 stable TMMs at the specific sites of a ferromagnetic meta-lattice at room temperature. We further develop soft X-ray vector ptycho-tomography to determine the magnetization vector and emergent magnetic field of the TMMs with a 3D spatial resolution of 10 nm. This spatial resolution is comparable to the magnetic exchange length of transition metals11, enabling us to probe monopole-monopole interactions. We find that the TMM and anti-TMM pairs are separated by 18.3 ± 1.6 nm, while the TMM and TMM, and anti-TMM and anti-TMM pairs are stabilized at comparatively longer distances of 36.1 ± 2.4 nm and 43.1 ± 2.0 nm, respectively. We also observe virtual TMMs created by magnetic voids in the meta-lattice. This work demonstrates that ferromagnetic meta-lattices could be used as a platform to create and investigate the interactions and dynamics of TMMs. Furthermore, we expect that soft X-ray vector ptycho-tomography can be broadly applied to quantitatively image 3D vector fields in magnetic and anisotropic materials at the nanoscale.
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Affiliation(s)
- Arjun Rana
- Department of Physics & Astronomy and California NanoSystems Institute, University of California, Los Angeles, Los Angeles, CA, USA
- STROBE Science and Technology Center, University of Colorado and NIST, Boulder, CO, USA
| | - Chen-Ting Liao
- STROBE Science and Technology Center, University of Colorado and NIST, Boulder, CO, USA
- JILA and Department of Physics, University of Colorado and NIST, Boulder, CO, USA
| | - Ezio Iacocca
- Department of Mathematics, Physics, and Electrical Engineering, Northumbria University, Newcastle upon Tyne, UK
- Center for Magnetism and Magnetic Nanostructures, University of Colorado, Colorado Springs, CO, USA
| | - Ji Zou
- Department of Physics & Astronomy and California NanoSystems Institute, University of California, Los Angeles, Los Angeles, CA, USA
| | - Minh Pham
- STROBE Science and Technology Center, University of Colorado and NIST, Boulder, CO, USA
- Department of Mathematics, University of California, Los Angeles, Los Angeles, CA, USA
| | - Xingyuan Lu
- Department of Physics & Astronomy and California NanoSystems Institute, University of California, Los Angeles, Los Angeles, CA, USA
- School of Physical Science and Technology, Soochow University, Suzhou, China
| | - Emma-Elizabeth Cating Subramanian
- STROBE Science and Technology Center, University of Colorado and NIST, Boulder, CO, USA
- JILA and Department of Physics, University of Colorado and NIST, Boulder, CO, USA
| | - Yuan Hung Lo
- Department of Physics & Astronomy and California NanoSystems Institute, University of California, Los Angeles, Los Angeles, CA, USA
- STROBE Science and Technology Center, University of Colorado and NIST, Boulder, CO, USA
| | - Sinéad A Ryan
- STROBE Science and Technology Center, University of Colorado and NIST, Boulder, CO, USA
- JILA and Department of Physics, University of Colorado and NIST, Boulder, CO, USA
| | - Charles S Bevis
- STROBE Science and Technology Center, University of Colorado and NIST, Boulder, CO, USA
- JILA and Department of Physics, University of Colorado and NIST, Boulder, CO, USA
| | - Robert M Karl
- STROBE Science and Technology Center, University of Colorado and NIST, Boulder, CO, USA
- JILA and Department of Physics, University of Colorado and NIST, Boulder, CO, USA
| | - Andrew J Glaid
- Departments of Chemistry, Physics, Materials Science and Engineering and Materials Research Institute, Penn State University, University Park, PA, USA
| | - Jeffrey Rable
- Departments of Chemistry, Physics, Materials Science and Engineering and Materials Research Institute, Penn State University, University Park, PA, USA
| | - Pratibha Mahale
- Departments of Chemistry, Physics, Materials Science and Engineering and Materials Research Institute, Penn State University, University Park, PA, USA
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA, USA
| | - Joel Hirst
- Materials and Engineering Research Institute, Sheffield Hallam University, Sheffield, UK
| | - Thomas Ostler
- Materials and Engineering Research Institute, Sheffield Hallam University, Sheffield, UK
- Department of Physics and Mathematics, University of Hull, Hull, UK
| | - William Liu
- Department of Physics & Astronomy and California NanoSystems Institute, University of California, Los Angeles, Los Angeles, CA, USA
- STROBE Science and Technology Center, University of Colorado and NIST, Boulder, CO, USA
| | - Colum M O'Leary
- Department of Physics & Astronomy and California NanoSystems Institute, University of California, Los Angeles, Los Angeles, CA, USA
- STROBE Science and Technology Center, University of Colorado and NIST, Boulder, CO, USA
| | - Young-Sang Yu
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Karen Bustillo
- National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Hendrik Ohldag
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - David A Shapiro
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Sadegh Yazdi
- Renewable and Sustainable Energy Institute, University of Colorado, Boulder, CO, USA
| | - Thomas E Mallouk
- Departments of Chemistry, Physics, Materials Science and Engineering and Materials Research Institute, Penn State University, University Park, PA, USA
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA, USA
| | - Stanley J Osher
- STROBE Science and Technology Center, University of Colorado and NIST, Boulder, CO, USA
- Department of Mathematics, University of California, Los Angeles, Los Angeles, CA, USA
| | - Henry C Kapteyn
- STROBE Science and Technology Center, University of Colorado and NIST, Boulder, CO, USA
- JILA and Department of Physics, University of Colorado and NIST, Boulder, CO, USA
| | - Vincent H Crespi
- Departments of Chemistry, Physics, Materials Science and Engineering and Materials Research Institute, Penn State University, University Park, PA, USA
| | - John V Badding
- Departments of Chemistry, Physics, Materials Science and Engineering and Materials Research Institute, Penn State University, University Park, PA, USA
| | - Yaroslav Tserkovnyak
- Department of Physics & Astronomy and California NanoSystems Institute, University of California, Los Angeles, Los Angeles, CA, USA
| | - Margaret M Murnane
- STROBE Science and Technology Center, University of Colorado and NIST, Boulder, CO, USA
- JILA and Department of Physics, University of Colorado and NIST, Boulder, CO, USA
| | - Jianwei Miao
- Department of Physics & Astronomy and California NanoSystems Institute, University of California, Los Angeles, Los Angeles, CA, USA.
- STROBE Science and Technology Center, University of Colorado and NIST, Boulder, CO, USA.
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