Direct Evidence of Topological Defects in Electron Waves through Nanoscale Localized Magnetic Charge

Phatak, Charudatta; Petford-Long, Amanda

doi:10.1021/acs.nanolett.8b02915

Title: Direct Evidence of Topological Defects in Electron Waves through Nanoscale Localized Magnetic Charge

Abstract

Topological concepts play an important role in, and provide unique insights into, many physical phenomena. In particular topological defects have become an active area of research due to their relevance to diverse systems including condensed matter and the early universe. These defects arise in systems during phase transitions or symmetry-breaking operations that lead to a specific configuration of the order parameter that is stable against external perturbations. In this work, we experimentally show that excitations or defects carrying magnetic charge in artificial spin ices introduce a topological defect in incident coherent electron waves. This results in the formation of a localized electron vortex beam carrying orbital angular momentum that is directly correlated with the magnetic charge. Furthermore, this work provides unique insight into the interaction of electrons with magnetically charged excitations and the effect on their topology thereby opening new possibilities to explore exotic scattering and quantum effects in nanoscale condensed-matter systems.

Authors:

^[1]; Petford-Long, Amanda ^[2]

Argonne National Lab. (ANL), Lemont, IL (United States)
Argonne National Lab. (ANL), Lemont, IL (United States); Northwestern Univ., Evanston, IL (United States)

Publication Date:: Mon Oct 22 00:00:00 EDT 2018

Research Org.:: Argonne National Lab. (ANL), Argonne, IL (United States)

Sponsoring Org.:: USDOE Office of Science (SC), Basic Energy Sciences (BES)

OSTI Identifier:: 1488567

Grant/Contract Number:: AC02-06CH11357

Resource Type:: Accepted Manuscript

Journal Name:: Nano Letters

Additional Journal Information:: Journal Volume: 18; Journal Issue: 11; Journal ID: ISSN 1530-6984

Publisher:: American Chemical Society

Country of Publication:: United States

Language:: English

Subject:: 36 MATERIALS SCIENCE; Lorentz transmission electron microscopy; Nanoscale artificial spin ices; vortex beams

Citation Formats


                    Phatak, Charudatta, and Petford-Long, Amanda. Direct Evidence of Topological Defects in Electron Waves through Nanoscale Localized Magnetic Charge.  United States: N. p., 2018. 
Web.  doi:10.1021/acs.nanolett.8b02915.

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                    Phatak, Charudatta, & Petford-Long, Amanda. Direct Evidence of Topological Defects in Electron Waves through Nanoscale Localized Magnetic Charge.  United States.  https://doi.org/10.1021/acs.nanolett.8b02915

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                    Phatak, Charudatta, and Petford-Long, Amanda. Mon .  
"Direct Evidence of Topological Defects in Electron Waves through Nanoscale Localized Magnetic Charge".  United States.  https://doi.org/10.1021/acs.nanolett.8b02915.  https://www.osti.gov/servlets/purl/1488567.

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@article{osti_1488567,

  title        = {Direct Evidence of Topological Defects in Electron Waves through Nanoscale Localized Magnetic Charge},

  author       = {Phatak, Charudatta and Petford-Long, Amanda},

  abstractNote = {Topological concepts play an important role in, and provide unique insights into, many physical phenomena. In particular topological defects have become an active area of research due to their relevance to diverse systems including condensed matter and the early universe. These defects arise in systems during phase transitions or symmetry-breaking operations that lead to a specific configuration of the order parameter that is stable against external perturbations. In this work, we experimentally show that excitations or defects carrying magnetic charge in artificial spin ices introduce a topological defect in incident coherent electron waves. This results in the formation of a localized electron vortex beam carrying orbital angular momentum that is directly correlated with the magnetic charge. Furthermore, this work provides unique insight into the interaction of electrons with magnetically charged excitations and the effect on their topology thereby opening new possibilities to explore exotic scattering and quantum effects in nanoscale condensed-matter systems.},

  doi          = {10.1021/acs.nanolett.8b02915},

  journal      = {Nano Letters},

  number       = 11,

  volume       = 18,

  place        = {United States},

  year         = {Mon Oct 22 00:00:00 EDT 2018},

  month        = {Mon Oct 22 00:00:00 EDT 2018}

}

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https://doi.org/10.1021/acs.nanolett.8b02915

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Figures / Tables:

Figure 1: (a) In-focus TEM image showing a region of the artificial spin ice and (b) the corresponding magnetic induction color map with inset colorwheel. The locations of magnetic monopole defects with the corresponding magnetic charges are identified in (b). (c) shows defocused electron diffraction patterns from the region enclosedmore »

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