Creation and observation of Hopfions in magnetic multilayer systems

Kent, Noah; Reynolds, Neal; Raftrey, David; Campbell, Ian T. G.; Virasawmy, Selven; Dhuey, Scott; Chopdekar, Rajesh V.; Hierro-Rodriguez, Aurelio; Sorrentino, Andrea; Pereiro, Eva; Ferrer, Salvador; Hellman, Frances; Sutcliffe, Paul; Fischer, Peter

doi:10.1038/s41467-021-21846-5

Title: Creation and observation of Hopfions in magnetic multilayer systems

Abstract

Among topological solitons, magnetic skyrmions are two-dimensional particle-like objects with a continuous winding of the magnetization, and magnetic Hopfions are three-dimensional objects that can be formed from a closed loop of twisted skyrmion strings. Theoretical models suggest that magnetic Hopfions can be stabilized in frustrated or chiral magnetic systems, and target skymions can be transformed into Hopfions by adapting their perpendicular magnetic anisotropy, but their experimental verification has been elusive so far. Here, we present an experimental study of magnetic Hopfions that are created in Ir/Co/Pt multilayers shaped into nanoscale disks, known to host target skyrmions. To characterize three-dimensional spin textures that distinguish Hopfions from target skyrmions magnetic images are recorded with surface-sensitive X-ray photoemission electron microscopy and bulk-sensitive soft X-ray transmission microscopy using element-specific X-ray magnetic circular dichroism effects as magnetic contrast. These results could stimulate further investigations of Hopfions and their potential application in three-dimensional spintronics devices.

Authors:

Kent, Noah ^[1]; Reynolds, Neal ^[2]; Raftrey, David ^[1]; Campbell, Ian T. G. ^[2]; Virasawmy, Selven ^[3]; Dhuey, Scott ^[3]; Chopdekar, Rajesh V. ^[3];

^[4];

^[5];

^[5]; Hellman, Frances ^[2];

^[6];

^[1]

Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Univ. of California, Santa Cruz, CA (United States)
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Univ. of California, Berkeley, CA (United States)
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Univ. of Oviedo (Spain)
ALBA Synchrotron, Cerdanyola del Vallès (Spain)
Durham Univ. (United Kingdom)

Publication Date:: Wed Mar 10 00:00:00 EST 2021

Research Org.:: Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States). Advanced Light Source (ALS) and The Molecular Foundry (TMF)

Sponsoring Org.:: USDOE Office of Science (SC), Basic Energy Sciences (BES). Materials Sciences & Engineering Division; European Union (EU)

OSTI Identifier:: 1713314

Grant/Contract Number:: AC02-05CH11231; H2020-MSCA-IF-2016-746958

Resource Type:: Accepted Manuscript

Journal Name:: Nature Communications

Additional Journal Information:: Journal Volume: 12; Journal Issue: 1; Journal ID: ISSN 2041-1723

Publisher:: Nature Publishing Group

Country of Publication:: United States

Language:: English

Subject:: 36 MATERIALS SCIENCE; Magnetic properties and materials

Citation Formats


                    Kent, Noah, Reynolds, Neal, Raftrey, David, Campbell, Ian T. G., Virasawmy, Selven, Dhuey, Scott, Chopdekar, Rajesh V., Hierro-Rodriguez, Aurelio, Sorrentino, Andrea, Pereiro, Eva, Ferrer, Salvador, Hellman, Frances, Sutcliffe, Paul, and Fischer, Peter. Creation and observation of Hopfions in magnetic multilayer systems.  United States: N. p., 2021. 
Web.  doi:10.1038/s41467-021-21846-5.

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                    Kent, Noah, Reynolds, Neal, Raftrey, David, Campbell, Ian T. G., Virasawmy, Selven, Dhuey, Scott, Chopdekar, Rajesh V., Hierro-Rodriguez, Aurelio, Sorrentino, Andrea, Pereiro, Eva, Ferrer, Salvador, Hellman, Frances, Sutcliffe, Paul, & Fischer, Peter. Creation and observation of Hopfions in magnetic multilayer systems.  United States.  https://doi.org/10.1038/s41467-021-21846-5

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                    Kent, Noah, Reynolds, Neal, Raftrey, David, Campbell, Ian T. G., Virasawmy, Selven, Dhuey, Scott, Chopdekar, Rajesh V., Hierro-Rodriguez, Aurelio, Sorrentino, Andrea, Pereiro, Eva, Ferrer, Salvador, Hellman, Frances, Sutcliffe, Paul, and Fischer, Peter. Wed .  
"Creation and observation of Hopfions in magnetic multilayer systems".  United States.  https://doi.org/10.1038/s41467-021-21846-5.  https://www.osti.gov/servlets/purl/1713314.

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@article{osti_1713314,

  title        = {Creation and observation of Hopfions in magnetic multilayer systems},

  author       = {Kent, Noah and Reynolds, Neal and Raftrey, David and Campbell, Ian T. G. and Virasawmy, Selven and Dhuey, Scott and Chopdekar, Rajesh V. and Hierro-Rodriguez, Aurelio and Sorrentino, Andrea and Pereiro, Eva and Ferrer, Salvador and Hellman, Frances and Sutcliffe, Paul and Fischer, Peter},

  abstractNote = {Among topological solitons, magnetic skyrmions are two-dimensional particle-like objects with a continuous winding of the magnetization, and magnetic Hopfions are three-dimensional objects that can be formed from a closed loop of twisted skyrmion strings. Theoretical models suggest that magnetic Hopfions can be stabilized in frustrated or chiral magnetic systems, and target skymions can be transformed into Hopfions by adapting their perpendicular magnetic anisotropy, but their experimental verification has been elusive so far. Here, we present an experimental study of magnetic Hopfions that are created in Ir/Co/Pt multilayers shaped into nanoscale disks, known to host target skyrmions. To characterize three-dimensional spin textures that distinguish Hopfions from target skyrmions magnetic images are recorded with surface-sensitive X-ray photoemission electron microscopy and bulk-sensitive soft X-ray transmission microscopy using element-specific X-ray magnetic circular dichroism effects as magnetic contrast. These results could stimulate further investigations of Hopfions and their potential application in three-dimensional spintronics devices.},

  doi          = {10.1038/s41467-021-21846-5},

  journal      = {Nature Communications},

  number       = 1,

  volume       = 12,

  place        = {United States},

  year         = {Wed Mar 10 00:00:00 EST 2021},

  month        = {Wed Mar 10 00:00:00 EST 2021}

}

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Title: Creation and observation of Hopfions in magnetic multilayer systems

Abstract

Citation Formats

Characterizing topography-induced contrast in photoelectron emission microscopy journal, July 2003

Let's twist again journal, March 2017

An Expression of Hopf's Invariant as an Integral journal, May 1947

Experimental observation of chiral magnetic bobbers in B20-type FeGe journal, April 2018

Skyrmion Knots in Frustrated Magnets journal, June 2017

Observation of room-temperature polar skyrmions journal, April 2019

Unwinding of a Skyrmion Lattice by Magnetic Monopoles journal, May 2013

Cryogenic PEEM at the Advanced Light Source journal, October 2012

Comments on Nonlinear Wave Equations as Models for Elementary Particles journal, September 1964

Real space soft x-ray imaging at 10 nm spatial resolution journal, January 2012

Nanoscale magnetic skyrmions in metallic films and multilayers: a new twist for spintronics journal, June 2016

Generation and stability of structurally imprinted target skyrmions in magnetic multilayers journal, September 2019

Three-Dimensional Dynamics of a Magnetic Hopfion Driven by Spin Transfer Torque journal, March 2020

Element-Specific Magnetic Hysteresis of Individual 18 nm Fe Nanocubes journal, April 2011

Chiral bobbers and skyrmions in epitaxial FeGe/Si(111) films journal, April 2018

Target-skyrmions and skyrmion clusters in nanowires of chiral magnets journal, January 2014

Propagation dynamics of spin excitations along skyrmion strings journal, January 2020

Binding a hopfion in a chiral magnet nanodisk journal, November 2018

Current-Driven Dynamics of Magnetic Hopfions journal, September 2019

Tunable room-temperature magnetic skyrmions in Ir/Fe/Co/Pt multilayers journal, July 2017

Magnetic skyrmions: advances in physics and potential applications journal, June 2017

Launching a new dimension with 3D magnetic nanostructures journal, January 2020

Direct Imaging of a Zero-Field Target Skyrmion and Its Polarity Switch in a Chiral Magnetic Nanodisk journal, November 2017

Topological Solitons book, January 2010

The stability of vortex-like structures in uniaxial ferromagnets journal, April 1999

Hopfions in chiral magnets journal, August 2018

Static Hopf Solitons and Knotted Emergent Fields in Solid-State Noncentrosymmetric Magnetic Nanostructures journal, October 2018

MISTRAL: a transmission soft X-ray microscopy beamline for cryo nano-tomography of biological samples and magnetic domains imaging journal, June 2015

Three-dimensional nanomagnetism journal, June 2017

Topological transformations of Hopf solitons in chiral ferromagnets and liquid crystals journal, January 2018

Characterizing topography-induced contrast in photoelectron emission microscopy
journal, July 2003

Let's twist again
journal, March 2017

An Expression of Hopf's Invariant as an Integral
journal, May 1947

Experimental observation of chiral magnetic bobbers in B20-type FeGe
journal, April 2018

Skyrmion Knots in Frustrated Magnets
journal, June 2017

Observation of room-temperature polar skyrmions
journal, April 2019

Unwinding of a Skyrmion Lattice by Magnetic Monopoles
journal, May 2013

Cryogenic PEEM at the Advanced Light Source
journal, October 2012

Comments on Nonlinear Wave Equations as Models for Elementary Particles
journal, September 1964

Real space soft x-ray imaging at 10 nm spatial resolution
journal, January 2012

Nanoscale magnetic skyrmions in metallic films and multilayers: a new twist for spintronics
journal, June 2016

Generation and stability of structurally imprinted target skyrmions in magnetic multilayers
journal, September 2019

Three-Dimensional Dynamics of a Magnetic Hopfion Driven by Spin Transfer Torque
journal, March 2020

Element-Specific Magnetic Hysteresis of Individual 18 nm Fe Nanocubes
journal, April 2011

Chiral bobbers and skyrmions in epitaxial FeGe/Si(111) films
journal, April 2018

Target-skyrmions and skyrmion clusters in nanowires of chiral magnets
journal, January 2014

Propagation dynamics of spin excitations along skyrmion strings
journal, January 2020

Binding a hopfion in a chiral magnet nanodisk
journal, November 2018

Current-Driven Dynamics of Magnetic Hopfions
journal, September 2019

Tunable room-temperature magnetic skyrmions in Ir/Fe/Co/Pt multilayers
journal, July 2017

Magnetic skyrmions: advances in physics and potential applications
journal, June 2017

Launching a new dimension with 3D magnetic nanostructures
journal, January 2020

Direct Imaging of a Zero-Field Target Skyrmion and Its Polarity Switch in a Chiral Magnetic Nanodisk
journal, November 2017

Topological Solitons
book, January 2010

The stability of vortex-like structures in uniaxial ferromagnets
journal, April 1999

Hopfions in chiral magnets
journal, August 2018

Static Hopf Solitons and Knotted Emergent Fields in Solid-State Noncentrosymmetric Magnetic Nanostructures
journal, October 2018

MISTRAL: a transmission soft X-ray microscopy beamline for cryo nano-tomography of biological samples and magnetic domains imaging
journal, June 2015

Three-dimensional nanomagnetism
journal, June 2017

Topological transformations of Hopf solitons in chiral ferromagnets and liquid crystals
journal, January 2018